PHYSIOLOGY OF DIGESTION IN BLATTIDAE . 387 
put them in separate dishes, washed in normal salt solution, 
and pressed out the contents. To the ten stomachs was added 
10 ce. of normal salt solution and the same to the eighty coeca. 
They were ground to a pulp in separate mortars, left two hours 
for the extraction of the enzyme, then to each was added the same 
amount of olive oil, and they were left seventy-two hours and 
titrated. The dish containing the coeca showed more acidity 
than the stomachs in the ratio 7: 5. 
As the histological structures of the stomach and coeca are 
the same, a truer comparison of their lipolytic functions would 
be expressed in terms of equal areas of their epithelial surfaces. 
Examinations of freshly dissected and of sectioned material 
reveals that the coeca have on the average half the length of 
the stomach, and a third of its diameter. So each coecum has 
one-sixth the surface of the stomach, and the eight coeca have 
eight-sixths the area of the stomach. ‘Thus the ratio of the 
epithelial areas of coeca and stomach is 8:6, and we have seen 
that the corresponding. ratios of the lipolytic effects is 7:5. 
This close approximation is striking and makes it evident that 
the fat-splitting action of the epithelium of the stomach and 
coeca per unit of area (or volume) is the same. The coeca are 
therefore not the special organs of secretion which various 
authors have considered them. 
The stomach and coeca are surely important organs for the 
secretion of digestive Juices, at least as regards lipolytic action. 
Most authors have placed them first as secreting organs. They 
really occupy an important second place, the crop occupying 
first place and being about twice as potent in digestion, at least 
of fats, as the stomach and coeca combined. 
Absorption in the stomach has been demonstrated by all 
investigators of insect digestion. All agree that the cells of the 
stomach have the power of absorbing food in liquid form. ‘The 
older writers endeavored to demonstrate the passage of fat 
globules as such from the lumen into the cytoplasm of the cells, 
but the fallacy of this is evident since it is known that fats are 
split to soluble products before absorption. The descriptions 
of the process vary greatly as given by various investigators. 
