366 ELDON W. SANFORD 
their findings may le in their considering cells immediately 
behind the stomach valve as intestinal cells, while they really 
belong to the stomach. 
Colon. The large intestine or colon is long and coiled in its 
position in the body. - Its epithelium consists of long, narrow 
cells which are thrown into rather regular folds. Under the 
folds tracheae and tracheal end cells may be seen. In the 
American cockroach the histological details may be seen well 
after using Flemming’s strong killing fluid. On the contrary, 
in the oriental cockroach, the structure is spoiled by Flemming’s 
fluid, as Petrunkevitch and Schliiter agree. In any case Pe- 
renyi’s fluid is satisfactory. The colon is divided from the small 
intestine by a fold or valve of the epithelium. The intima is 
raised into significant mounds over each of the cells, but no 
hairs are evident, as described for Blatta orientalis. The func- 
tion of the colon is not absorptive, at least I have not found 
it so, nor have many other authors except Frenzel, and his. ob- 
servations have since been disproved by later investigators. 
Simroth and Mingazzini have stated that certain sacs of the 
colon were absorptive in Lamellicorn larvae, but their deserip- 
tions indicate that there was no real absorption, but mere passage 
through pores. Berlese has described a similar case. 
Rectum. ‘The rectum is the last part of the digestive canal 
and terminates at the anus. It is surounded by a thin muscular 
layer. The so-called rectal glands are six lobes of very long cells 
which bulge far out into the lumen. Their cells do not quite 
reach the muscular layer, but leave small interspaces, in which 
tracheae ramify. The cells of the glands have a distinct intima, 
but no chitinous filaments. This intima is continuous between 
the glands and dips down almost to the muscular layer,. there 
being almost no cells between: 
EXPERIMENTS IN PHYSIOLOGY 
Oesophagus. The function of the oesophagus is merely to 
conduct food into the crop or to retain it for a time if the crop 
is quite full. The thick intima evidently precludes all secretion 
and absorption here. No globules of absorbed fat were ever seen 
in the cells. 
