DIGESTIVE PROCESSES IN PLANAEIJi:. 
217 
Passage of Fat and Excretory Gteanules into the 
Parenchyma. 
Some of the fat absorbed by the columnar cells is not 
digested but passed out in globules at their bases into the 
parenchyma (see fig. 2 ; on the right a fat-globule is being 
extruded). These globules are taken up by some amoeboid 
wandei’ing cells (fig. 14), and also by the yolk-cells (fig. 12) 
and the large parenchyma cells (fig. 17). How these globules 
reach the interior of the yolk-cells I have not been able to 
ascertain. Any digestive power of an amoeboid nature in the 
yolk-cells or even in the parenchyma-cells is extremely 
unlikely. Nevertheless it is very striking that after feeding, 
the yolk-cells which lie in proximity to the intestine are 
crowded with fat-globules, whereas in unfed specimens the 
yolk-cells contain scai’cely anything but yolk-globules. After 
feeding, fat-globules are numerous at the bases of the 
columnar cells, and lying free in the meshwork of the paren- 
chyma (fig. 14). The parenchyma-cells also contain numerous 
excretory granules, massed together in vacuoles (fig. 17). 
It would be expected that in an animal like Planaria devoid 
of an anus, the excretory products would be shed into the 
intestine to make their way out to the exterior by the 
pharynx. 
An examination of a very large amount of material, con- 
sisting of some hundreds of slides, has afforded no evidence 
in support of this view. Not only have I been unable to see 
any extrusion of waste matter into the intestine, but a careful 
search through numerous sections has failed to show any 
trace of extruded excreta in the shape of the cliaracteristic 
yellow concretions in the lumen of the intestine. Are they 
so soluble that they are all removed when lying free in the 
intestine by the process of preparing the material for 
sectioning ? If not, it is difficult to explain how they are 
removed from the body of the Planarian to the exterior. 
I wish to express my thanks to Dr. Roaf, of the Department 
