376 ELDON W. SANFORD 
as follows: after eighteen hours, small amounts; after thirty 
hours, moderate to considerable amounts; after thirty-two hours, 
large amounts (fig. 6). So oleic acid is readily absorbed into the 
epithelial cells. The absorption is more rapid than in the case 
of fats, as might be expected, for fats must be split before ab- 
sorption, while with oleic acid this is unnecessary. 
In order to discover the relation between fats and fatty acids 
during the digestion of fat, a paste of sugar and olive oil was used 
as food; into the paste a generous amount of Nile blue sulphate 
was stirred. After three days the animal was dissected and the 
crop sectioned in a freezing microtome. The sections showed 
blue globules of fat in the epithelial cells. These were surely fat, 
for the stain colors fat blue, fatty acids red. Within the lumen 
of the crop and sticking to the intima a red mass was found, 
this was fatty acid derived from the fat eaten. In another case 
oil was stained bright red with Sudan III and fed. Subsequent 
frozen sections showed many red globules in the epithelial cells. 
I have already stated that in some cases a large meal of fat 
may not all be utilized until about two months later. In these 
cases there is a continual absorption of fat in the crop through- 
out the whole period, as I have demonstrated by making a series 
of preparations at various intervals through the period of utili- 
zation of a crop’s content of fat. Figure 5 shows a stage two 
months after a large meal was eaten. Absorption is almost 
completed, though some recently absorbed globules are seen in 
the region of the cells nearest the lumen. The middle region 
of the cells is occupied by large globules. The material of the 
globules is apparently being utilized, for the region between 
them and the body cavity is occupied by many small globules. 
These represent fatty material in process of passage (as soluble 
products) from the large storage globules to the blood in the 
body cavity. The large globules must represent storage products, 
ready to be utilized when needed. We have already seen that 
the lumen of the crop is important for storage of food, and now 
we see that the epithelium of the crop is important for storage, 
too, but in another sense. 
