214 
(1. AKX(3J,D. 
Intka-cellular T)[GEST10N. 
After all the fat hits been absorbed, and when all the 
gland cells are empty (fig. 10), true intra-cell ular digestion 
(phagocytosis) commences. 
The columnar cells push out at their free ends long pseudo- 
podial extensions into the lumen of the intestine, and shortly 
afterwards large vacuoles appear in which masses of red 
blood-corpuscles are seen (fig. 3). 
At this stage, one and a quarter hours after feeding, the 
selective action of the columnar cells is very noticeable, for 
only the red-corpuscles are ingested, but none of the leuco- 
cytes. The latter are ingested last of all, some forty-eight 
hours after feeding (fig. 6). 
The digestion of the red corpuscles takes place very slowly. 
Kven ninety-six hours after feeding (fig. 8) ihey may be seen 
intact in some vacuoles. 
As digestion proceeds, the corpuscles lose their shape (fig. 
b, h.e.), till at last the vacuoles contain an amorphous mass of 
particles, consisting chiefly of the envelopes of the corpuscles, 
which are stained by the methylene blue. 
The leucocytes are ingested singly, and a vacuolar space 
soon appears round them. 
The leucocytes which lie in the lumen of the intestine do 
not appear to undergo any change at all. Even after forty- 
eight or fifty-two hours they can be seen scattered about in 
the lumen, their cytoplasm stained orange by the acid stain, 
and the nuclear inembi-ane and the chromatin in the nucleus 
quite intact. But immediately a vacuole has formed round 
them after ingestion (figs. 6 and 7, L.) their staining reaction 
changes. The cytoplasm then takes a pink colour, due to 
the basic fuchsin, their nuclear contents become diffused, 
and shortly afterwards the separate chromatin masses are no 
longer distinguishable (fig. 9). 
This marked and rapid change in the staining reaction is 
undoubtedly due to the fluid in the vacuole secreted by the 
surrounding cytoplasm. 
