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Mr. Darwin's extremely conscientious method of work is backed up by the utmost patience and industry. Hence it is that not even his earliest works are out of date, in spite of the rapid advance of inquiry in every direction. Whenever there appears to be the least necessity for a revision of one of these he straightway sets about the task, and brings the work up to the present level of knowledge. The "Origin of Species" has reached its sixteenth thousand, the "Naturalists' Voyage Round the World" its twelfth thousand, and "The Descent of Man" its tenth thousand. And when it is remembered that all these have been brought out in five or six European languages, the immense influence they have exercised upon the scientific thought of the time will be at once apparent. For the last ten years, or, perhaps, more, he has been engaged in collecting all the information obtainable upon the physiology of carnivorous plants belonging to the order Drosera, supplemented by his own exhaustive observations and experiments, and has published the result in a beautifully illustrated volume, entitled, "Insectivorous Plants" (Murray). In looking over the work we cannot but be struck with the extremely careful manner in which the conclusions of others have been tested, and, in some important cases, to the utter discredit of their "marvellous " statements. For instance, a Mrs. Treat published in the American Naturalist an account of an experiment in which she pinned a living fly at a very short distance from D. filiformis, and declared that after about an hour and a half the tentacles on the leaf bent towards and inclosed it. Mr. Darwin, on the contrary, finds that actual contact is invariably necessary to the action of the tentacles. It had also been supposed that inorganic substances had scarcely any effect upon the plant, but the author finds that the minutest particles of glass, cotton, hair, certain chemicals, &c., excited contraction, though drops of water had no effect whatever. Some idea of the delicacy of the experiments made may be gathered from the fact that particles of the inorganic matters mentioned above, weighing as little as the [1/76000] of a grain were applied to the plant, and always produced sensible contraction though the duration of it was short, and even the [1/19760000] of a grain of phosphate of ammonia was sufficient to excite the peculiar action of the tentacles. The salts of sodium always excited contraction, but did not poison the plant; while most of the salts of potassium did not excite it and did poison it. The poison of the cobra is dried and sent to this country in a form somewhat resembling gum Arabic, as the reader probably knows, and when a small portion of this was applied to the plant it occasioned vigorous contraction of the leaf, but had no effect on its life, though the same quantity would probably have been fatal to the strongest man. The idea of poisoning a plant is a strange one, but the organisation of this order of plants has a good deal in common with members of the animal kingdom. We have seen that the most deadly organic poison known, that of the cobra, is resisted, while salts of potassium are fatal to sundews. One of the most singular features of the order is the possession of small glands, situated at the end of the tentacles, which enclose the insect in the leaf, enabling it to perform the functions of digestion and assimilation. Albumenised substances brought into contact with these glands, excite the secretions, which, according to Professor Frankland's analysis, has a strong chemical resemblance to pepsine, and behaves in the same manner in dissolving animal matter. That the plant feeds upon the insects it entraps there can now beno doubt whatever, and its life is thus maintained. But it appears capable of takin only a limited amount of such nourishment, and if overfed dies. Perhaps the few points indicated here after a hasty glance at the work, will be sufficient to show how interesting is the subject dealt with. We shall, perhaps, return to it on a future occasion.