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INSECTIVOROUS PLANTS.

THE name of Mr. Darwin is so constantly associated with the origin of species and the descent of man that many of our readers will find it difficult to believe that a volume of his, consisting of 450 pages, contains nothing on these subjects, nor has any reference to them except that very collateral reference which, from his point of view, every treatise on natural history must have.

The theory of natural selection is never enforced in these pages so as to make the descent of man from an inferior type probable, nor is the preservation of favoured races in the struggle for life brought prominently before our attention. The book, corresponds precisely to its title, and concerns a tiny, and hitherto almost unnoticed, por tion of the animal and vegetable kingdoms—a scrap of border land where the two meet—where the flies and insects of the one become, the food, not of other and larger animals, but of plants which are furnished by nature with every convenience for grasping, devouring, absorbing, and assimilating their prey. There is certainly no other person in England but the author who could have produced this book, for the minuteness of its researches into matters microscopically small is without parallel except among some German naturalists. Whatever may be the judgment of posterity, respecting the origin, of species as propounded by Darwin there can be no doubt that he will ever be regarded as one of the most successful students of nature, having a rare faculty of observation, and having brought together an enormous multitude of inductions. He has rendered the most important services to naturalists of every kind and degree by his works on Geology, Orchids, Coral Reeſs, Volcanoes, and Climbing Plants, not to speak of those works of world-wide celebrity which have made him the admiration of many, and the scorn and derision of many more. This volume on the various contrivances by which orchids are fertilized by insects was some what similar to the present in its material and treatment, but as time goes on, and Darwin's experience ripens, his writings have in them an increased wealth of facts and observations that charms and enriches every student of nature who reads them.

Dr. Hooker, in an address delivered before the British Association in Belfast last year, called attention to carnivorous plants, and dwelt particularly (as Professor Asa Gray has done in the Action) on the power of true digestion possessed by Drosera and Dionaea. Dr. Nitschke also has given the bibliography of Drosera, but no one has entered into the subject so fully and ably as Mr. Darwin. Fifteen years ago he was surprised by finding how large a number of insects were caught by the leaves of the common sun-dew (Drosera rotundifolia) on a heath in Sussex. This led him to further investigation, and the work before us is the result. The leaves and tentacles of the sun-dew are first described and the manner in which insects are captured by them. The proof is then given of their glands having the power of absorption; and the blending of animal and vegetable life in the assimilation which follows leads us to reflect how easily, if such were the Creator's will, the animal, vegetable, and mineral kingdoms (as we call them) that now exist might give birth to another kingdom equally varied and distinct.

After recapitulating the observations on Drosera Rotundifolia, which occupy half the volume, the author goes on to describe the Dionaea Muscipula and other plants, which also capture and absorb insects. It should be remembered—and this is the lesson to be derived from the work—that while ordinary plants of the higher classes procure the requisite inorganic elements from the soil by means of their roots, and absorb carbonic acid from the atmosphere by means of their stems and leaves, there is a class of plants which digest and subsequently absorb animal matter. These are all the Droseraceae, Pinguicula, and Nepenthes, nor can it be doubted that other species will almost certainly have to be added to this class. These plants can dissolve matter out of pollen, seeds, bits of leaves, and other vegetable substances. Their glands absorb also the salts of ammonia brought by the rain.

Some other plants can absorb ammonia by their glandular hairs. Again there is a second class of plants which cannot digest, but absorb the products of the decay of the animals which they capture, and these are the Utricularia and its close allies. It is probable that Sarracenia and Darlingtonia should be added to this class. There is again a third class of plants which feed, as is now generally admitted, on the products of the decay of vegetable matter, such as the bird's nest orchids. In the last place, there is a well-known fourth class of parasites, such as the mistletoe, which are nourished by the juices of living plants. Most of the plants, however, belonging to these four classes, obtain part of their carbon, like ordinary species, ſrom the atmosphere. It would be superfluous to recommend this book to botanists and naturalists in general. It is already a standard work in its own department.