DIGESTIVE PROCESSES IN PLANARI^. 
209 
Some cells from the intestine of a planarian which has been 
without food for some seven or eight days are shown in 
PI. 17 , fig. 13. 
The cells of the intestine are of two sorts : 
(1) Long, irregularly columnar cells. The cytoplasm of 
the cell (fig. 13) consists of a clear protoplasmic network^ 
enclosing several large vacuoles at its distal end, the vacuoles 
towards the middle of the cell being smaller and fewer. The 
proximal part of the cell consists of very much denser cyto- 
plasm, in which the reticulum is very fine and close, showing 
an almost fibrillar structure at its extreme end. The spaces 
between the network take the acid stain, but the network 
itself is stained by the basic colours, so that the proximal end 
of the cell where the reticulum is very dense is much darker 
than the rest. 
In this part lies the nucleus, which is small in proportion 
to the cytoplasm. The nucleus is round or ovoid, with a 
deeply staining membrane, and a nucleolus which is stained 
bright blue by the methylene blue. 
In an animal which has been starved for fifteen days the 
vacuoles in the cytoplasm are more numerous and larger 
(fig. 11). The cytoplasm around each vacuole is denser and 
more granular than elsewhere, but a definite membi’ane 
cannot be made out. 
(2) (xoblet-shaped gland-cells, only half as large, or less, 
than the former, invariably with a small nucleus extremely 
irregular in outline, and taking the basic fuchsin stain very 
markedly. The cytoplasm is very granular, and is peculiar 
in having a greater affinity for basic than acid stains, 
staining as deeply as the nuclear material. It is full of large 
vacuoles, in which now and again is to be seen a residue also 
stained by the methylene blue (tigs. 11 and 13.) 
Absoki'tion of Pat. 
We will deal with the functions and history of these gland 
cells first. There is generally one of them to every ten of the 
