1918] DuPorte—The Proventriculus 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 also 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 (Pl. VI, 4). The 
mesenteron contained only small pieces (Pl. VII). A similar re- 
