ter were well embraced in a few hours; whereas after 25 hrs. only a very few tentacles were inflected over the other objects. The bits of paper, moss, and quill were then removed from these leaves, and bits of raw meat placed on them! and now all the tentacles were soon energetically inflected.

Again, particles of coal-cinder (weighing rather more than the flies used in the last experiment) were placed on the centres of three leaves: after an interval of 19 hrs. one of the particles was tolerably well embraced; a second by a very few tentacles; and a third by none. I then removed the particles from the two latter leaves, and put on them recently killed flies. These were fairly well embraced in 7 1-2 hrs. and thoroughly after 20 1-2 hrs.; the tentacles remaining inflected for many subsequent days. On the other hand, the one leaf which had in the course of 19 hrs. embraced the bit of cinder moderately well, and to which no fly was given, after an additional 33 hrs. (i.e., in 52 hrs. from the time when the cinder was put on) was completely re-expanded and ready to act again.

From these and numerous other experiments not worth giving, it is certain that inorganic substances, or such organic substances as are not attacked by the secretion, act much less quickly and efficiently than organic substances yielding soluble matter which is absorbed. Moreover, I have met with very few excep

tions to the rule, and these exceptions apparently depended on the leaf having been too recently in action, that the tentacles remain clasped for a much longer time over organic bodies of the nature just specified than over those which are not acted on by the secretion, or over inorganic objects.

DIGESTION.

When the glands on the disc are excited either by the absorption of nitrogenous matter or by mechanical irritation, their secretion increases in quantity and becomes acid. They likewise transmit some influence to the glands of the exterior tentacles, causing them to secrete more copiously; and their secretion likewise becomes acid. With animals, according to Schiff, mechanical irritation excites the glands of the stomach to secrete an acid, but not pepsin. Now, I have every reason to believe (though the fact is not fully established), that although, the glands of Drosera are continually secreting viscid fluid to replace that lost by evaporation, yet they do not secrete the ferment proper for digestion when mechanically irritated, but only after absorbing certain matter, probably of a nitrogenous nature. I infer that this is the case, as the secretion from a large number of leaves which had been irritated by particles of glass placed on their discs did not digest

albumen; and more especially from the analogy of Dionaea and Nepenthes. In like manner, the glands of the stomach of animals secrete pepsin, as Schiff asserts, only after they have absorbed certain soluble substances, which he designates as peptogenes. There is, therefore, a remarkable parallelism between the glands of Drosera and those of the stomach in the secretion of their proper acid and ferment.

The secretion completely dissolves albumen, muscle, fibrin, areola tissue. cartilage, the fibrous basis of bone, gelatin, chondrin, casein in the state in which it exists in milk, and gluten which has been subjected to weak hydrochloric acid. Syntonin and legumin excite the leaves so powerfully and quickly that there can hardly be a doubt that both would be dissolved by the secretion. The secretion failed to digest fresh gluten, apparently from its injuring the glands, though some was absorbed. Raw meat, unless in very small bits, and large pieces of albumen, &c., likewise injure the leaves, which seem to suffer, like animals, from a surfeit. I know not whether the analogy is a real one, but it is worth notice that a decoction of cabbage leaves is far more exciting and probably nutritious to Drosera than an infusion made with tepid water; and boiled cabbages are far more nutritious, at least to man, than the uncooked leaves. The most striking of all the cases,

though not really more remarkable than many others, is the digestion of so hard and tough a substance as cartilage. The dissolution of pure phosphate of lime, of bone, dentine, and especially enamel, seems wonderful; but it depends merely on the long-continued secretion of an acid; and this is secreted for a longer time under these circumstances than under any others. It was interesting to observe that as long as the acid was consumed in dissolving the phosphate of lime, no true digestion occurred; but that as soon as the bone was completely decalcified, the fibrous basis was attacked and liquefied with the greatest ease. The twelve substances above enumerated, which are completely dissolved by the secretion are likewise dissolved by the gastric juice of the higher animals; and they are acted on in the same manner, as shown by the rounding of the angles of albumen, and more especially by the manner in which the transverse striae of the fibres of muscle disappear.

The secretion of Drosera and gastric juice were both able to dissolve some element or impurity out of the globulin and haematin employed by me. The secretion also dissolved something out of chemically prepared casein, which is said to consist of two substances; and although Schiff asserts that casein in this state is not attacked by gastric juice, he might easily have overlooked a minute quantity of

some albuminous would detect and absorb. Again, fibro-cartilage, though not properly dissolved, is acted on in the same manner, both by the secretion of Drosera and gastric juice. But this substance, as well as the so-called haematin used by me, ought perhaps to have been classed with indigestible substances.

matter, which Drosera

That gastric juice acts by means of its ferment, pepsin, solely in the presence of an acid, is well established; and we have excellent evidence that a ferment is present in the secretion of Drosera, which likewise acts only in the presence of an acid; for we have seen that when the secretion is neutralized by minute drops of the solution of an alkali, the digestion of albumen is completely stopped, and that on the addition of a minute dose of hydrochloric acid it immediately recommences.

The nine following substances, or classes of substances, namely, epidermic productions, fibro-elastic tissue, mucin, pepsin, urea, chitine, cellulose, guncotton, chlorophyll, starch, fat and oil, are not acted on by the secretion of Drosera; nor are they, as far as is known, by the gastric juice of animals. Some soluble matter, however, was extracted from the mucin, pepsin, and chlorophyll, used by me, both by the secretion and by artificial gastric juice.

The several substances, which are completely dissolved by the secretion, and which are