152 Miscellaneous. Investigation of the Phenomena of Digestion in Insects. By M. Felix Plateau. (An abstract of his paper in the ' Memoires de l'Acad. Roy. de Belgique,' tome xli. 1874. Communicated by the author.) The uecessitj 7 of having recourse to animals possessing an organi-zation resembling our own for the purpose of solving the various problems of human physiology has led to the carrying out of a multi-tude of experimental researches, the results of which when brought together and discussed constitute the comparative physiology of the Vertebrata, which, however, still exhibits important gaps arising from the preponderance that has been given to the study of certain classes to the neglect of the rest. The division which has received most attention next to the Vertebrata is that of the Arthropoda. We already possess valuable treatises on the locomotion, the innervation, the cir-culation, the animal heat, the secretory phenomena, and especially the embryonic development of these animals ; but it will be remarked that digestion has been left almost entirely in the shade. Attracted by the novelty of the subject, but without losing sight of the difficulty of the task, we have endeavoured to fill up this gap by repeating on a small scale what so many others have done on a large scale for the Mammalia — by feeding Articulate animals, follow-ing, often step by step, the modifications of their food in the diges-tive tube, analyzing as far as possible the liquids secreted by the walls and glandular appendages of the latter, attempting artificial diges-tions, &c* Although our investigations have for several years embraced the whole of the group, we have thought it better at present to publish only what relates to the Insects t; and we do this with the confidence derived from work performed with minute care, but also with the conviction that we have done no more than to place a landmark as the starting-point for future studies. Our observations, and especially our experiments, have led us to results some of which are in complete disagreement with what we find stated in recent classical treatises. Could it well be otherwise ? The authors of the works of which I speak had before them as ma-terials nothing but almost exclusively anatomical data, of which they have taken the best advantage in their power by depending upon analogies of form. To be as brief as possible, I shall confine myself to an abstract of the summary which concludes my memoir. When the salivary glands are not diverted from their original function to become silk-glands, poison-glands, &c, they secrete a neutral or alkaline liquid, possessing, at least in the case of one of * Respect for priority makes it our duty to point out to the reader that the first experiments in artificial digestion by means of the digestive liquids of an Arthropod were made by M. Emile Blanchard in his researches on the Scorpion ('Organisation du Regne Animal,' Arachnides, p. 66). t The description of the phenomena of digestion in the Myriopoda, the Crustacea, and the Arachnida will appear hereafter.