120 Psyche [December 



suit was obtained with crickets which had been starved for 

 several days and then fed on grains of wheat. The crop contained 

 large bits both of the hull and of the starchy endosperm. The 

 mesenteron contained several large bits of hull but no pieces of 

 endosperm as large as those in the crop (PI. VII, 2, 3, 4). 



It will be seen from the foregoing that as a grating for the exclu- 

 sion of large particles from the mesenteron the proventriculus has, 

 in the cricket, little or no efficiency, since it allows even fragments 

 of quartz to pass through it. Indeed a study of the arrangement 

 of the backward directed teeth and the strong muscular coat will 

 make it evident that particles caught in the proventriculus will be 

 forced towards the mesenteron. The action of the proventriculus 

 might be compared with that of the rollers in a mill; anything 

 caught between the rollers is carried onward, if it is strong enough 

 to resist the breaking power of the rollers it will come out unaltered 

 on the other side, if not it will be crushed. 



In many insects the teeth of the proventriculus are so poorly 

 developed that they can have little or no triturating action. In 

 others this organ serves some special purpose as in the honey sac 

 of the bee (Cheshire), or the combined pump and valve of the house 

 fly (Hewitt). In the cricket, however, the structure of the pro- 

 ventriculus and the condition of the food after passing through it 

 leave no room for doubt that this organ has a definite triturating 

 function. 



References. 



1. Straus-Durckheim, H. 1828. Considerations generales sur 



r Anatomic comparee des Animaux articules. Pp. 263-265. 



2. Burmeister. 1836. Manualof Entomology (Shuckard's trans.). 



London. Pp. 408-409. 



3. Plateau, F. 1874. Recherches sur les Phenomenes de la 



Digestion chez les Insectes. Mem. de I'Acad. Roy. des Sc. 

 des lettres et des Beaux-Arts de Belgique. Bruxelles, XLI. 

 Pp. 104-106. 



4. Miall, L. C. and Denny, A. 1886. The Structure and Life 



History of the Cockroach. London. Pp. 117-130, 131. 



5. Emery, C. 1888. Ueber den Sogenannten Kaumagen einiger 



Ameisen. Zeitschr. f. Wissen. Zool. XLVI, 378-412. 



6. Kolbe, H. J. 1893. Einfiihrung in d. Kenntniss d. Insekten, 



Berlin. Pp. 576, 590. 



