1918J DuPorte — The P roventriculus of Gryllus pennsylvanicus Burm. 119 



Examination of the structure of the proventriculus with its 

 complicated system of teeth — the sharp denticles fitted for cutting 

 and tearing, the lateral teeth fitted for crushing and grinding — and 

 its efficient mechanism for powerful compression can hardly fail to 

 convince one that this organ has a definite triturating function; 

 but the evidence does not lie in the structure alone but ^Iso in a 

 consideration of the condition of the food in the crop, the pro- 

 ventriculus and the mesenteron. 



Plateau, one of the foremost and most authoritative exponents 

 of the theory that the proventriculus is exclusively a strainer, has 

 shown in support of his contention that if a cockroach feeds on 

 food rich in cellulose, which is not digestible in the crop, fragments 

 are found unaltered as to form and size in the mesenteron. If it 

 consumes an abundance of farinaceous food, starch granules which 

 escape digestion in the crop are found uncrushed in the mesenteron. 

 To the writer this evidence does not seem conclusive because if 

 the proventriculus were efficient as a strainer, all large particles 

 should be excluded from the mesenteron no matter what their 

 nature, and we should find much solid food in the crop and only 

 liquid food or finely divided solid food in the mesenteron. On the 

 other hand, if the proventriculus has a masticating action, tough 

 substances such as cellulose would be imperfectly triturated, while 

 bits of food as small as starch grains might easily escape further 

 comminution. The condition of the food in the different sections 

 of the canal would depend on the nature of the food ingested. If 

 the food is soft and easily crushed the contents of the crop and 

 mesenteron will be similar to those described where the straining 

 action is postulated. If the food contains hard or tough particles, 

 not easily crushed, these will be forced through the proventriculus 

 and solid particles of food will be found, not only in the crop, but 

 also in the mesenteron. 



An examination of the digestive canal of crickets which had been 

 fed on miscellaneous food, including dead crickets and locusts, 

 revealed the fact that the particles of chitin, quartz and woody 

 tissue found in the proventriculus and mesenteron were fully as 

 large as any found in the crop (PI. VI, 1, 2, 3). 



The crop of crickets which had been fed on dead insects con- 

 tained large particles of soft animal tissue (PI. VI, 4). The 

 mesenteron contained only small pieces (PI. VII). A similar re- 



