Miscellaneous. 355 



Posterior wing lobed, projecting at the middle of the outer 

 margin, crossed transversely by two bands of bro^7n. 



Exp. 1^0 inch. 



Hah. Brazil. 



In the collection of Dr. Staudinger. May be a variety of 

 the last. 



MISCELLANEOUS. 



Note on tlie Phenomena of Digestion in the Cockroach (Periplaneta 

 americana, L.). By M. Felix Plateau. 



The Editors of the ' Annals of Natural History ' have given (in 

 volume xvi. 1875, p. 152) a summary of my " Recherches sur lea 

 phenomenes de la digestion chez les Insectes"*. In the number for 

 April 1876, p. 333, they have reproduced, under the title "On the 

 Functions of the Glands of the Digestive Apparatus of Insects," 

 an abstract of the memoir of M. Jousset de Bellesme entitled 

 " Recherches experimentales sur la digestion des Insectes et en 

 particulier de la Biatte " (8vo, Paris, 1875). 



The publication of M. Jousset's work has called forth on my part 

 a well-founded claim of priorityf, since M. Jousset reproduced, a 

 year after myself, nearly all my results. A discussion has also re- 

 sulted, as we did not agree on certain points, of which the principal 

 may be characterized as follows. Relying on a long series of experi- 

 ments, I had put forward in my memoir of 1874 that the digestive 

 juices of insects are alkaline or neutral, never acid. M. Jousset 

 asserts the contrary, and says that in the Blatta the liquid of the 

 caeca of the middle intestine is slightly acid. 



The present note contains the results of a study which I have 

 just made of the phenomena of digestion in Periplaneta ameri- 

 cana. The following is an abstract of it. 



The aliments when swallowed accumulate in the crop and undergo 

 the action of the secretion (which is most frequently alkaline) of 

 the salivary glands ; there the feculent substances are transformed 

 into glucose. This first product of digestion is absorbed on the 

 spot, and is met with no more in the rest of the digestive tube. 



The valvular apparatus (gizzard), which by no means plays the 

 part of a trituratory organ, allows the matter in course of digestion 

 to slide in small quantities into the middle intestine. That region 

 receives the juice secreted by eight glandular caeca, which is ordi- 

 narily alkaline, never acid., neutralizing the acidity that the contents 

 of the crop may have acquired after a long stay in that organ, trans- 

 forming the albuminoids into soluble and assimilable bodies analo- 

 gous to the peptones J, and forming emulsion of the fats. 



* M4m. de I'Acad. Roy. de Belgique, tome xli. 1874. 



t Comptes Rendus, 1876, vol. Ixxxii. p. 340. 



X The action of the secretion of the caeca of the cockroach on the 

 albuminoids has been demonstrated by M. Jousset. I am happy to con- 

 firm his results ; only this secretion is not acid. 



