Digestive Processes in Arachnids. Bg II. M. Bernard. 435 
found in the stercoral pocket, and they give the same chemical 
reactions ; that they are, in fact, guanin. 
How does this faecal matter come to be in the peritoneal cells 
outside the alimentary canal? Two answers to this question are 
suggested by our observations on Obisium and Scorpio above 
described. 
We find in Obisium the digesting cells of the gut crowded from 
end to end with food-globules (fig. 1), the peritoneal cells adjoining 
having apparently nothing else to do than to pass on the assimilated 
fluids. In Scorpio , we have the digesting cells more specialized, 
each containing a large vacuole capable of reducing only a limited 
number of these food-globules. A large number of them, therefore, 
pass out of the endodermal digesting cells into the adjoining meso- 
dermal cells, probably returning again to be assimilated in the 
digesting vacuoles. While, however, they are thus stored up, the 
peritoneal cells occasionally commence to assimilate them for them- 
selves, reducing them, when they do so, into minute crystal-like 
bodies, essentially similar to those within the gut. The round 
globules found by Bertkau in the peritoneal cells of Atypus can, I 
think, be nothing else than food-globules which have passed through 
the wall of the gut, probably as into a temporary storehouse. 
Unfortunately, as none of my preparations of Araneids show any 
food-globules in the peritoneal cells, I have been unable to ascertain 
whether they are there subjected to any digestive process. But this 
is what may take place in the Araneids. Food-globules pass out of 
the digesting cells into the adjoining mesodermal cells, and may 
there be, normally or abnormally, digested, the fsecal remains being 
carried away by the Malpighian tubules. 
A second method of accounting for these faecal “ crystals ” in the 
peritoneal cells and the Malpighian tubules is by supposing that the 
digesting diverticula are so branched and their lumina are so narrow 
that the faecal masses resulting from digestion within the more distal 
portions of these tubules fail to find their way into the central canal, 
and have to he got rid of by passing through the wall of the gut and 
into the Malpighian tubules. The difficulty of getting rid of faeces 
from the digestive tubules has indeed already been suggested as an 
objection to the supposition that the so-called “ liver” diverticula 
might he digesting, and not secreting, organs. It is obvious that this 
difficulty could be got over if the faecal “crystals,” or at least a 
portion of them, could pass out of the gut and be discharged through 
the Malpighian tubules. 
Fig. 5 represents part of a section of the abdomen of an emaciated 
house-spider caught in mid-winter. It represents parts of four 
digesting diverticula, between which are seen the peritoneal cells, 
which in this case were highly vacuolated, the nuclei being suspended 
on threads, and portions of two Malpighian tubules. The digesting 
cells contain round granules which I take to be food-globules, though 
