JOURNAL 
OF THE 
ROYAL MICROSCOPICAL SOCIETY. 
AUGUST 1893. 
TRANSACTIONS OF THE SOCIETY. 
VIII . — Notes on some of the Digestive Processes in Arachnids. 
By Henry M. Bernard, M.A. Cantab., F.Z.S., 
from the Huxley Research Laboratory. 
( Read 19 th April , 1893.) 
Plate VI. 
Observations on the digestive processes of the Arachnids have 
hitherto, as far as I am aware, been mainly confined to the Araneids. 
A comparative treatment of the subject suggested itself to me during 
my researches on the comparative anatomy and morphology of the 
EXPLANATION OF PLATE VI. 
Fig. 1. — Two digestive cells of a Chernetid (one only in outline). Beneath, i. e. 
outside the basement membrane, are seen the vacuolated peritoneal cells. The 
faecal “ crystals” are seen streaming out into the lumen of the gut between the cells. 
Fig. 2. — The different stages, as seen under the Microscope, in the reduction of 
the homogeneous food-globules into the faecal “ crystals.” 
Fig. 3. — Three digestive cells of Scorpio. The food-globules are being assimi- 
lated within large vacuoles, there being one vacuole in each cell, The distal end of 
the cell is a dense cushion of granular staining protoplasm, through which the faecal 
“ crystals ” pass. The peritoneal cells are filled with food-globules apparently tem- 
porarily stored up. Here and there these globules are being digested and reduced 
to “ crystals,” which escape into the blood and are found in the blood-corpuscles. 
Fig. 4. — A group of digestive cells of Scorpio crowded out of the epithelium, 
and floating free in the lumen of the gut. The nuclei are completely obscured. 
Fig. 5. — Part of section of the abdomen of an emaciated house-spider ; small 
parts of four digesting diverticula are seen ; the faecal crystals are massed close to 
the basement membrane. Two fragments of Malpighian tubules are seen running 
through the highly vacuolated peritoneal cells; these tubules are crowded with 
faecal “ crystals.” 
Fig. 6. — Portion of a longitudinal section of an abdominal diverticulum of a 
Galeodes grsecus; the epithelium is completely disorganized. A small mass of 
stained coagulum (containing moth’s scales) riot yet converted into food-globules 
in the middle. The faecal “crystals” have sunk to the ventral side of the tube. 
They are seen in a bright yellow fluid, which is the assimilable product of the food- 
globules. This is also seen dorsally on the outside of the tube, having passed 
through the basement membrane, to mix with the blood. No trace of a peritoneal 
layer is visible. 
Fig. 7. — A group of digesting cells of Galeodes araneoides (?) showing mulberry- 
like food-masses breaking down into faecal “crystals.” These food-masses have 
1893. ' 2 ii 
