374 ELDON W. SANFORD 
not given. In some cases the cells were found so full of fat that 
they appeared as solid black, excluding all other structures from 
view. The fat found in the cells had evidently got there from 
the lumen of the crop, seemingly through pores. It was really a 
clear case of absorption by diffusion. In late stages of digestion 
fat globules were found lying free in the pouches of the body 
cavity behind the epithelial folds. 
On the basis of Petrunkevitch’s work, Sinety attacked the 
problem. He fed with fat fifteen hours and found fat beginning 
to appear in the cells. This is said not to be of special signifi-- 
cance, but to represent fat which is absorbed from the blood by 
the cells and stored in them as reserve food material. His belief 
is that these reserves explain Petrunkevitch’s figures. 
Schliiter also based his work on that of Petrunkevitch, but used 
a special feeding method, namely, smearing of fat on the body 
and reliance on the cleaning activities of the animals to get the 
food into the mouth. He found that fat appeared in the cells and 
also in the blood lacunae fifteen to twenty minutes after feeding 
began. He assumed that most of this must have gotten through 
the intima and cells unchanged, for the splitting of fat to soluble 
products and their absorption could hardly have occurred so 
soon. The appearance was only seen in those parts of the crop 
where fat actually lay against the cells. A complicating factor 
was some residual fat, which was present in the cells when the 
experiment began. He never found cells completely filled with 
fat, but did find places where fat had rushed in from the lumen 
through a hole in the intima and had filled cells. Thus he ex- 
plains Petrunkevitch’s appearances of completely filled cells. 
In other experiments he starved animals eight days and fed them 
fat one to three days. None was subsequently found in the 
cells, but it was found there after eight days of sugar feeding. 
This led to his assumption that fat is made from carbohydrate 
in the body and is sometimes stored as fat in the cells. 
Jordan in his text-book on digestion in invertebrates admits 
that much carbohydrate may be absorbed in the crop, but is doubt- 
ful as to fat, for the work of Sinety and Schliiter indicates that 
fat in the cells may be a product of metabolism. 
