DIGESTIVE ORGANS OF INSECTS. 



211 



To engage in a minute description of the end- 

 less variations in the structure of the digestive 

 organs, presented in the innumerable tribes 

 which compose this class of animals, would 

 be incompatible with the limits of this treatise. 

 I shall content myself, therefore, with giving a 

 few illustrations of their prin- 

 cipal varieties, selected from 

 those in which the leading 

 characters of structure are 

 most strongly marked. I shall, 

 with this view, exhibit first one 

 of the simplest forms of the 

 alimentary organs, as they oc- 

 cur in the Mantis religiosa, 

 (Linn.) which is a purely car- 

 nivorous insect, belonging to 

 the order of Orthoptera. Fig. 

 317 represents those of this 

 insect, freed from their attach- 

 ments, and separated from the 

 body. The whole canal, as is 

 seen, is perfectly straight: it 

 commences by an oesophagus 

 (o), of great length, which is succeeded by a 



Grylli, possessed the faculty of ruminating their food; but this 

 error has been refuted by Marcel de Serres, who has offered satis- 

 factory evidence that in no insect is the food subjected to a true 

 rumination, or second mastication, by the organs of the mouth. 

 See Annales du Museum, xx. 51 and 364. 



