tentacles showed only a trace of inflection. Bits of meat were then placed on three of these leaves, but in 24 hrs. only slight and irregular inflection occurred, proving that the leaves had been greatly injured. Two of the leaves to which meat had not been given had their discal glands dry and much injured. Minute drops of a strong solution of one part to 109 of water (4 grs. to 1 oz.) were added to the secretion round several glands, but did not produce nearly so plain an effect as the drops of a much weaker solution of the acetate. Particles of the dry citrate were placed on six glands; two of these moved some way towards the centre, and then stood still, being no doubt killed; three others curved much farther inwards, and were then fixed; one alone reached the centre. Five leaves were immersed, each in thirty minims of a solution of one part to 437 of water; so that each received 1/16 of a grain; after about 1 hr. some of the outer tentacles became inflected, and the glands were oddly mottled with black and white.
These glands, in from 4 hrs. to 5 hrs., became whitish and opaque, and the protoplasm in the cells of the tentacles was well aggregated. By this time two of the leaves were greatly inflected, but the three others not much more inflected than they were before. Nevertheless two fresh leaves, after an immersion respectively for 2 hrs. and 4 hrs. in the solution, were not killed; for on being left for 1 hr. 30 m. in a solution of one part of carbonate of ammonia to 218 of water, their tentacles became more inflected, and there was much aggregation. The glands [page 201] of two other leaves, after an immersion for 2 hrs. in a stronger solution, of one part of the citrate to 218 of water, became of an opaque, pale pink colour, which before long disappeared, leaving them white. One of these two leaves had its blade and tentacles greatly inflected; the other hardly at all; but the protoplasm in the cells of both was aggregated down to the bases of the tentacles, with the spherical masses in the cells close beneath the glands blackened. After 24 hrs. one of these leaves was colourless, and evidently dead.
Sulphate of Quinine.—Some of this salt was added to water, which is said to dissolve 1/1000 part of its weight. Five leaves were immersed, each in thirty minims of this solution, which tasted bitter. In less than 1 hr. some of them had a few tentacles inflected. In 3 hrs. most of the glands became whitish, others dark-coloured, and many oddly mottled. After 6 hrs. two of the leaves had a good many tentacles inflected, but this very moderate degree of inflection never increased.
One of the leaves was taken out of the solution after 4 hrs., and placed in water; by the next morning some few of the inflected tentacles had re-expanded, showing that they were not dead; but the glands were still much discoloured. Another leaf not included in the above lot, after an immersion of 3 hrs. 15 m., was carefully examined; the protoplasm in the cells of the outer tentacles, and of the short green ones on the disc, had become strongly aggregated down to their bases; and I distinctly saw that the little masses changed their positions and shapes rather rapidly; some coalescing and again separating. I was surprised at this fact, because quinine is said to arrest all movement in the white corpuscles of the blood; but as, according to Binz,* this is due to their being no longer supplied with oxygen by the red corpuscles, any such arrestment of movement could not be expected in Drosera. That the glands had absorbed some of the salt was evident from their change of colour; but I at first thought that the solution might not have travelled down the cells of the tentacles, where the protoplasm was seen in active movement. This view, however, I have no doubt, is erroneous, for a leaf which had been immersed for 3 hrs. in the quinine solution was then placed in a little solution of one part of carbonate of ammonia to 218 of water; and in 30 m. the glands and the upper cells of the tentacles became intensely black, with the protoplasm presenting a very unusual appearance; for it [page 202] had become aggregated into reticulated dingy-coloured masses, having rounded and angular interspaces. As I have never seen this effect the previous action of the quinine. These reticulated masses were watched for some time, but did not change their forms; so that the protoplasm no doubt had been killed by the combined action of the two salts, though exposed to them for only a short time.
Another leaf, after an immersion for 24 hrs. in the quinine solution, became somewhat flaccid, and the protoplasm in all the cells was aggregated. Many of the aggregated masses were discoloured, and presented a granular appearance; they were spherical, or elongated, or still more commonly consisted of little curved chains of small globules. None of these masses exhibited the least movement, and no doubt were all dead.
Half-minims of the solution were placed on the discs of six leaves; after 23 hrs. one had all its tentacles, two had a few, and the others none inflected; so that the discal glands, when irritated by this salt, do not transmit any strong motor impulse to the outer tentacles. After 48 hrs. the glands on the discs of all six leaves were evidently much injured or quite killed. It is clear that this salt is highly poisonous.* Acetate of Quinine.—Four leaves were immersed, each in thirty minims of a solution of one part to 437 of water. The solution was tested with litmus paper, and was not acid. After only 10 m. all four leaves were greatly, and after 6 hrs. immensely, inflected. They were then left in water for 60 hrs., but never re-expanded; the glands were white, and the leaves evidently dead. This salt is far more efficient than the sulphate in causing inflection, and, like that salt, is highly poisonous.
Nitrate of Quinine.—Four leaves were immersed, each in thirty minims of a solution of one part to 437 of water. After 6 hrs. there was hardly a trace of inflection; after 22 hrs. three of the leaves were moderately, and the fourth slightly inflected; so that this salt induces, though rather slowly, well-marked inflection. These leaves, on being left in water for 48 hrs., almost *Binz found several years ago (as stated in ‘The Journal of Anatomy and Phys.’ November 1872, p. 195) that quinia is an energetic poison to low vegetable and animal organisms. Even one part added to 4000 parts of blood arrests the movements of the white corpuscles, which become “rounded and granular.” In the tentacles of Drosera the aggregated masses of protoplasm, which appeared killed by the quinine, likewise presented a granular appearance. A similar appearance is caused by very hot water. [page 203] completely re-expanded, but the glands were much discoloured. Hence this salt is not poisonous in any high degree. The different action of the three foregoing salts of quinine is singular.
Digitaline.—Half-minims of a solution of one part to 437 of water were placed on the discs of five leaves. In 3 hrs. 45 m. Some of them had their tentacles, and one had its blade, moderately inflected. After 8 hrs. three of them were well inflected; the fourth had only a few tentacles inflected, and the fifth (an old leaf) was not at all affected. They remained in nearly the same state for two days, but the glands on their discs became pale. On the third day the leaves appeared much injured. Nevertheless, when bits of meat were placed on two of them, the outer tentacles became inflected. A minute drop (about 1/20 of a minim) of the solution was applied to three glands, and after 6 hrs. all three tentacles were inflected, but next day had nearly re-expanded; so that this very small dose of 1/28800 of a grain (.00225 mg.) acts on a tentacle, but is not poisonous. It appears from these several facts that digitaline causes inflection, and poisons the glands which absorb a moderately large amount.
Nicotine.—The secretion round several glands was touched with a minute drop of the pure fluid, and the glands were instantly blackened; the tentacles becoming inflected in a few minutes. Two leaves were immersed in a weak solution of two drops to 1 oz., or 437 grains, of water. When examined after 3 hrs. 20 m., only twenty-one tentacles on one leaf were closely inflected, and six on the other slightly so; but all the glands were blackened, or very dark-coloured, with the protoplasm in all the cells of all the tentacles much aggregated and dark-coloured. The leaves were not quite killed, for on being placed in a little solution of carbonate of ammonia (2 grs. to 1 oz.) a few more tentacles became inflected, the remainder not being acted on during the next 24 hrs.
Half-minims of a stronger solution (two drops to 1/2 oz. of water) were placed on the discs of six leaves, and in 30 m. all those tentacles became inflected; the glands of which had actually touched the solution, as shown by their blackness; but hardly any motor influence was transmitted to the outer tentacles. After 22 hrs. most of the glands on the discs appeared dead; but this could not have been the case, as when bits of meat were placed on three of them, some few of the outer tentacles were inflected in 24 hrs. Hence nicotine has a great tendency to blacken the glands and to induce aggregation [page 204] of the protoplasm, but, except when pure, has very moderate power of inducing inflection, and still less power of causing a motor influence to be transmitted from the discal glands to the outer tentacles. It is moderately poisonous.
Atropine.—A grain was added to 437 grains of water, but was not all dissolved; another grain was added to 437 grains of a mixture of one part of alcohol to seven parts of water; and a third solution was made by adding one part of valerianate of atropine to 437 of water.
Half-minims of these three solutions were placed, in each case, on the discs of six leaves; but no effect whatever was produced, excepting that the glands on the discs to which the valerianate was given were slightly discoloured. The six leaves on which drops of the solution of atropine in diluted alcohol had been left for 21 hrs. were given bits of meat, and all became in 24 hrs. fairly well inflected; so that atropine does not excite movement, and is not poisonous. I also tried in the same manner the alkaloid sold as daturine, which is believed not to differ from atropine, and it produced no effect. Three of the leaves on which drops of this latter solution had been left for 24 hrs. were likewise given bits of meat, and they had in the course of 24 hrs. a good many of their submarginal tentacles inflected.
Veratrine, Colchicine, Theine.—Solutions were made of these three alkaloids by adding one part to 437 of water. Half-minims were placed, in each case; on the discs of at least six leaves, but no inflection was caused, except perhaps a very slight amount by the theine.
Half-minims of a strong infusion of tea likewise produced, as formerly stated, no effect. I also tried similar drops of an infusion of one part of the extract of colchicum, sold by druggists, to 218 of water; and the leaves were observed for 48 hrs., without any effect being produced. The seven leaves on which drops of veratrine had been left for 26 hrs. were given bits of meat, and after 21 hrs. were well inflected. These three alkaloids are therefore quite innocuous.
Curare.—One part of this famous poison was added to 218 of water, and three leaves were immersed in ninety minims of the filtered solution.
In 3 hrs. 30 m. some of the tentacles were a little inflected; as was the blade of one; after 4 hrs. After 7 hrs. the glands were wonderfully blackened, showing that matter of some kind had been absorbed. In 9 hrs. two of the leaves had most of their tentacles sub-inflected, but the inflection did not increase in the course of 24 hrs. One of these leaves, after being immersed for 9 hrs. in the solution, was placed in water, and by next morning had largely re-expanded; [page 205] the other two, after their immersion for 24 hrs., were likewise placed in water, and in 24 hrs. were considerably re-expanded, though their glands were as black as ever. Half-minims were placed on the discs of six leaves, and no inflection ensued; but after three days the glands on the discs appeared rather dry, yet to my surprise were not blackened. On another occasion drops were placed on the discs of six leaves, and a considerable amount of inflection was soon caused; but as I had not filtered the solution, floating particles may have acted on the glands. After 24 hrs. bits of meat were placed on the discs of three of these leaves, and next day they became strongly inflected. As I at first thought that the poison might not have been dissolved in pure water, one grain was added to 437 grains of a mixture of one part of alcohol to seven of water, and half-minims were placed on the discs of six leaves. These were not at all affected, and when after a day bits of meat were given them, they were slightly inflected in 5 hrs., and closely after 24 hrs. It follows from these several facts that a solution of curare induces a very moderate degree of inflection, and this may perhaps be due to the presence of a minute quantity of albumen. It certainly is not poisonous. The protoplasm in one of the leaves, which had been immersed for 24 hrs., and which had become slightly inflected, had undergone a very slight amount of aggregation—not more than often ensues from an immersion of this length of time in water.
Acetate of Morphia.—I tried a great number of experiments with this substance, but with no certain result. A considerable number of leaves were immersed from between 2 hrs. and 6 hrs. in a solution of one part to 218 of water, and did not become inflected. Nor were they poisoned; for when they were washed and placed in weak solutions of phosphate and carbonate of ammonia, they soon became strongly inflected, with the protoplasm in the cells well aggregated. If, however, whilst the leaves were immersed in the morphia, phosphate of ammonia was added, inflection did not rapidly ensue. Minute drops of the solution were applied in the usual manner to the secretion round between thirty and forty glands; and when, after an interval of 6 m:, bits of meat, a little saliva, or particles of glass, were placed on them, the movement of the tentacles was greatly retarded. But on other occasions no such retardation occurred. Drops of water similarly applied never have any retarding power. Minute drops of a solution of sugar of the same strength (one part to 218 of water) sometimes retarded the subsequent action of meat and of particles of glass, and [page 206] sometimes did not do so. At one time I felt convinced that morphia acted as a narcotic on Drosera, but after having found in what a singular manner immersion in certain non-poisonous salts and acids prevents the subsequent action of phosphate of ammonia, whereas other solutions have no such power, my first conviction seems very doubtful.
Extract of Hyoscyamus.—Several leaves were placed, each in thirty minims of an infusion of 3 grs. of the extract sold by druggists to 1 oz. of water. One of them, after being immersed for 5 hrs. 15 m., was not inflected, and was then put into a solution (1 gr. to 1 oz.) of carbonate of ammonia; after 2 hrs. 40 m. it was found considerably inflected, and the glands much blackened. Four of the leaves, after being immersed for 2 hrs. 14 m., were placed in 120 minims of a solution (1 gr. to 20 oz.) of phosphate of ammonia; they had already become slightly inflected from the hyoscyamus, probably owing to the presence of some albuminous matter, as formerly explained, but the inflection immediately increased, and after 1 hr. was strongly pronounced; so that hyoscyamus does not act as a narcotic or poison.
Poison from the Fang of a Living Adder.—Minute drops were placed on the glands of many tentacles; these were quickly inflected, just as if saliva had been given them, Next morning, after 17 hrs. 30 m., all were beginning to re-expand, and they appeared uninjured.
Poison from the Cobra.—Dr. Fayrer, well known from his investigations on the poison of this deadly snake, was so kind as to give me some in a dried state. It is an albuminous substance, and is believed to replace the ptyaline of saliva.* A minute drop (about 1/20 of a minim) of a solution of one part to 437 of water was applied to the secretion round four glands; so that each received only about 1/38400 of a grain (.0016 mg.). The operation was repeated on four other glands; and in 15 m.
several of the eight tentacles became well inflected, and all of them in 2 hrs. Next morning, after 24 hrs., they were still inflected, and the glands of a very pale pink colour. After an additional 24 hrs. they were nearly re-expanded, and completely so on the succeeding day; but most of the glands remained almost white.
Half-minims of the same solution were placed on the discs of three leaves, so that each received 1/960 of a grain (.0675 mg.); in 4 hrs. 15 m. the outer tentacles were much inflected; and after 6 hrs.
30 m. those on two of the leaves were closely inflected and the blade of one; the third leaf was only moderately affected. The leaves remained in the same state during the next day, but after 48 hrs.
re-expanded.
Three leaves were now immersed, each in thirty minims of the solution, so that each received 1/16 of a grain, or 4.048 mg. In 6 m. there was some inflection, which steadily increased, so that after 2 hrs. 30 m.
all three leaves were closely inflected; the glands were at first somewhat darkened, then rendered pale; and the protoplasm within the cells of the tentacles was partially aggregated. The little masses of protoplasm were examined after 3 hrs., and again after 7 hrs., and on no other occasion have I seen them undergoing such rapid changes of form. After 8 hrs. 30 m. the glands had become quite white; they had not secreted any great quantity of mucus. The leaves were now placed in water, and after 40 hrs. re-expanded, showing that they were not much or at all injured. During their immersion in water the protoplasm within the cells of the tentacles was occasionally examined, and always found in strong movement.
Two leaves were next immersed, each in thirty minims of a much stronger solution, of one part to 109 of water; so that each received 1/4 of a grain, or 16.2 mg; After 1 hr. 45 m. the sub-marginal tentacles were strongly inflected, with the glands somewhat pale; after 3 hrs. 30 m.
both leaves had all their tentacles closely inflected and the glands white. Hence the weaker solution, as in so many other cases, induced more rapid inflection than the stronger one; but the glands were sooner rendered white by the latter. After an immersion of 24 hrs. some of the tentacles were examined, and the protoplasm, still of a fine purple colour, was found aggregated into chains of small globular masses.
These changed their shapes with remarkable quickness. After an immersion of 48 hrs. they were again examined, and their movements were so plain that they could easily be seen under a weak power. The leaves were now placed in water, and after 24 hrs. (i.e. 72 hrs. from their first immersion) the little masses of protoplasm, which had become of a dingy purple, were still in strong movement, changing their shapes, coalescing, and again separating.
In 8 hrs. after these two leaves had been placed in water (i.e. in 56 hrs. after their immersion in the solution) they began to re-expand, and by the next morning were more expanded. After an additional day (i.e. on the fourth day after their immersion in the solution) they were largely, but not quite fully [page 208] expanded. The tentacles were now examined, and the aggregated masses were almost wholly redissolved; the cells being filled with homogeneous purple fluid, with the exception here and there of a single globular mass. We thus see how completely the protoplasm had escaped all injury from the poison. As the glands were soon rendered quite white, it occurred to me that their texture might have been modified in such a manner as to prevent the poison passing into the cells beneath, and consequently that the protoplasm within these cells had not been at all affected. Accordingly I placed another leaf, which had been immersed for 48 hrs. in the poison and afterwards for 24 hrs. in water, in a little solution of one part of carbonate of ammonia to 218 of water; in 30 m. the protoplasm in the cells beneath the glands became darker, and in the course of 24 hrs. the tentacles were filled down to their bases with dark-coloured spherical masses. Hence the glands had not lost their power of absorption, as far as the carbonate of ammonia is concerned.
From these facts it is manifest that the poison of the cobra, though so deadly to animals, is not at all poisonous to Drosera; yet it causes strong and rapid inflection of the tentacles, and soon discharges all colour from the glands. It seems even to act as a stimulant to the protoplasm, for after considerable experience in observing the movements of this substance in Drosera, I have never seen it on any other occasion in so active a state. I was therefore anxious to learn how this poison affected animal protoplasm; and Dr. Fayrer was so kind as to make some observations for me, which he has since published.* Ciliated epithelium from the mouth of a frog was placed in a solution of.03 gramme to 4.6 cubic cm. of water; others being placed at the same time in pure water for comparison. The movements of the cilia in the solution seemed at first increased, but soon languished, and after between 15 and 20 minutes ceased; whilst those in the water were still acting vigorously. The white corpuscles of the blood of a frog, and the cilia on two infusorial animals, a Paramaecium and Volvox, were similarly affected by the poison. Dr. Fayrer also found that the muscle of a frog lost its irritability after an immersion of 20 m. in the solution, not then responding to a strong electrical current. On the other hand, the movements of the cilia on the mantle of an Unio were not always arrested, even when left for a considerable time in a very strong solution. On the whole, it seems that the poison of the cobra acts far more injuriously on the protoplasm of the higher animals than on that of Drosera.
There is one other point which may be noticed. I have occasionally observed that the drops of secretion round the glands were rendered somewhat turbid by certain solutions, and more especially by some acids, a film being formed on the surfaces of the drops; but I never saw this effect produced in so conspicuous a manner as by the cobra poison. When the stronger solution was employed, the drops appeared in 10 m. like little white rounded clouds. After 48 hrs. the secretion was changed into threads and sheets of a membranous substance, including minute granules of various sizes.
Camphor.—Some scraped camphor was left for a day in a bottle with distilled water, and then filtered. A solution thus made is said to contain 1/1000 of its weight of camphor; it smelt and tasted of this substance. Ten leaves were immersed in this solution; after 15 m. five of them were well inflected, two showing a first trace of movement in 11 m. and 12 m.; the sixth leaf did not begin to move until 15 m. had elapsed, but was fairly well inflected in 17 m. and quite closed in 24 m.; the seventh began to move in 17 m., and was completely shut in 26 m. The eighth, ninth, and tenth leaves were old and of a very dark red colour, and these were not inflected after an immersion of 24 hrs.; so that in making experiments with camphor it is necessary to avoid such leaves. Some of these leaves, on being left in the solution for 4 hrs., became of a rather dingy pink colour, and secreted much mucus; although their tentacles were closely inflected, the protoplasm within the cells was not at all aggregated. On another occasion, however, after a longer immersion of 24 hrs., there was well marked aggregation. A solution made by adding two drops of camphorated spirits to an ounce of water did not act on one leaf; whereas thirty minims added to an ounce of water acted on two leaves immersed together.
M. Vogel has shown* that the flowers of various plants do not wither so soon when their stems are placed in a solution of camphor as when in water; and that if already slightly withered, they recover more quickly. The germination of certain seeds is also accelerated by the solution. So that camphor acts as a stimulant, and it is the only known stimulant for plants. I were made in 1798 by B. S. Barton. [page 210] wished, therefore, to ascertain whether camphor would render the leaves of Drosera more sensitive to mechanical irritation than they naturally are. Six leaves were left in distilled water for 5 m. or 6 m., and then gently brushed twice or thrice, whilst still under water, with a soft camel-hair brush; but no movement ensued. Nine leaves, which had been immersed in the above solution of camphor for the times stated in the following table, were next brushed only once with the same brush and in the same manner as before; the results are given in the table. My first trials were made by brushing the leaves whilst still immersed in the solution; but it occurred to me that the viscid secretion round the glands would thus be removed, and the camphor might act more effectually on them. In all the following trials, therefore, each leaf was taken out of the solution, waved for about 15 s. in water, then placed in fresh water and brushed, so that the brushing would not allow the freer access of the camphor; but this treatment made no difference in the results.
Column 1: Number of Leaves. Column 2: Length of Immersion in the Solution of Camphor. Column 3: Length of Time between the Act of Brushing and the Inflection of the Tentacles. Column 4: Length of Time between the Immersion of the Leaves in the Solution and the First Sign of the Inflection of the Tentacles.
11 m. 30 s.
strongly marked.: 7 m.
m. 30 s.
6 m. 30 s.
: 6 m. 30 s.
inflection.: 5 m.
inflection.: 5 m.
Other leaves were left in the solution without being brushed; one of these first showed a trace of inflection after 11 m.; a second after 12 m.; five were not inflected until 15 m. had [page 211] elapsed, and two not until a few minutes later. On the other hand, it will be seen in the right-hand column of the table that most of the leaves subjected to the solution, and which were brushed, became inflected in a much shorter time. The movement of the tentacles of some of these leaves was so rapid that it could be plainly seen through a very weak lens.
Two or three other experiments are worth giving. A large old leaf, after being immersed for 10 m. in the solution, did not appear likely to be soon inflected; so I brushed it, and in 2 m. it began to move, and in 3 m. was completely shut. Another leaf, after an immersion of 15 m., showed no signs of inflection, so was brushed, and in 4 m. was grandly inflected. A third leaf, after an immersion of 17 m., likewise showed no signs of inflection; it was then brushed, but did not move for 1 hr.; so that here was a failure. It was again brushed, and now in 9 m. a few tentacles became inflected; the failure therefore was not complete.
We may conclude that a small dose of camphor in solution is a powerful stimulant to Drosera. It not only soon excites the tentacles to bend, but apparently renders the glands sensitive to a touch, which by itself does not cause any movement. Or it may be that a slight mechanical irritation not enough to cause any inflection yet gives some tendency to movement, and thus reinforces the action of the camphor. This latter view would have appeared to me the more probable one, had it not been shown by M. Vogel that camphor is a stimulant in other ways to various plants and seeds.
Two plants bearing four or five leaves, and with their roots in a little cup of water, were exposed to the vapour of some bits of camphor (about as large as a filbert-nut), under a vessel holding ten fluid oz.
After 10 hrs. no inflection ensued; but the glands appeared to be secreting more copiously. The leaves were in a narcotised condition, for on bits of meat being placed on two of them, there was no inflection in 3 hrs. 15 m., and even after 13 hrs. 15 m. only a few of the outer tentacles were slightly inflected; but this degree of movement shows that the leaves had not been killed by an exposure during 10 hrs. to the vapour of camphor.
Oil of Caraway.—Water is said to dissolve about a thousandth part of its weight of this oil. A drop was added to an ounce of water and the bottle occasionally shaken during a day; but many minute globules remained undissolved. Five leaves were immersed in this mixture; in from 4 m. to 5 m. there was some inflection, which became moderately pronounced in two or [page 212] three additional minutes. After 14 m.
all five leaves were well, and some of them closely, inflected. After 6 hrs. the glands were white, and much mucus had been secreted. The leaves were now flaccid, of a peculiar dull-red colour, and evidently dead. One of the leaves, after an immersion of 4 m., was brushed, like the leaves in the camphor, but this produced no effect. A plant with its roots in water was exposed under a 10-oz. vessel to the vapour of this oil, and in 1 hr. 20 m. one leaf showed a trace of inflection.
After 5 hrs. 20 m. the cover was taken off and the leaves examined; one had all its tentacles closely inflected, the second about half in the same state; and the third all sub-inflected. The plant was left in the open air for 42 hrs., but not a single tentacle expanded; all the glands appeared dead, except here and there one, which was still secreting. It is evident that this oil is highly exciting and poisonous to Drosera.
Oil of Cloves.—A mixture was made in the same manner as in the last case, and three leaves were immersed in it. After 30 m. there was only a trace of inflection which never increased. After 1 hr. 30 m. the glands were pale, and after 6 hrs. white. No doubt the leaves were much injured or killed.
Turpentine.—Small drops placed on the discs of some leaves killed them, as did likewise drops of creosote. A plant was left for 15 m. under a 12-oz. vessel, with its inner surface wetted with twelve drops of turpentine; but no movement of the tentacles ensued. After 24 hrs. the plant was dead.
Glycerine.—Half-minims were placed on the discs of three leaves: in 2 hrs. some of the outer tentacles were irregularly inflected; and in 19 hrs. the leaves were flaccid and apparently dead; the glands which had touched the glycerine were colourless. Minute drops (about 1/20 of a minim) were applied to the glands of several tentacles, and in a few minutes these moved and soon reached the centre. Similar drops of a mixture of four dropped drops to 1 oz. of water were likewise applied to several glands; but only a few of the tentacles moved, and these very slowly and slightly. Half-minims of this same mixture placed on the discs of some leaves caused, to my surprise, no inflection in the course of 48 hrs. Bits of meat were then given them, and next day they were well inflected; notwithstanding that some of the discal glands had been rendered almost colourless. Two leaves were immersed in the same mixture, but only for 4 hrs.; they were not inflected, and on being afterwards left for 2 hrs. 30 m. in a solution (1 gr. to 1 oz.) of carbonate of ammonia, their glands were blackened, their tentacles inflected, and the protoplasm within their cells aggregated. It appears [page 213] from these facts that a mixture of four drops of glycerine to an ounce of water is not poisonous, and excites very little inflection; but that pure glycerine is poisonous, and if applied in very minute quantities to the glands of the outer tentacles causes their inflection.
The Effects of Immersion in Water and in various Solutions on the subsequent Action of Phosphate and Carbonate of Ammonia.—We have seen in the third and seventh chapters that immersion in distilled water causes after a time some degree of aggregation of the protoplasm, and a moderate amount of inflection, especially in the case of plants which have been kept at a rather high temperature. Water does not excite a copious secretion of mucus. We have here to consider the effects of immersion in various fluids on the subsequent action of salts of ammonia and other stimulants. Four leaves which had been left for 24 hrs. in water were given bits of meat, but did not clasp them. Ten leaves, after a similar immersion, were left for 24 hrs. in a powerful solution (1 gr. to 20 oz.) of phosphate of ammonia, and only one showed even a trace of inflection. Three of these leaves, on being left for an additional day in the solution, still remained quite unaffected. When, however, some of these leaves, which had been first immersed in water for 24 hrs., and then in the phosphate for 24 hrs. were placed in a solution of carbonate of ammonia (one part to 218 of water), the protoplasm in the cells of the tentacles became in a few hours strongly aggregated, showing that this salt had been absorbed and taken effect.
A short immersion in water for 20 m. did not retard the subsequent action of the phosphate, or of splinters of glass placed on the glands; but in two instances an immersion for 50 m. prevented any effect from a solution of camphor. Several leaves which had been left for 20 m. in a solution of one part of white sugar to 218 of water were placed in the phosphate solution, the action of which was delayed; whereas a mixed solution of sugar and the phosphate did not in the least interfere with the effects of the latter. Three leaves, after being immersed for 20 m.
in the sugar solution, were placed in a solution of carbonate of ammonia (one part to 218 of water); in 2 m. or 3 m. the glands were blackened, and after 7 m. the tentacles were considerably inflected, so