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. 



