68 THE PHYSIOLOGY OF THE COMMON CRAYFISH. 
similar to that of the pancreatic juice of the higher 
animals. 
The mixture thus produced, which answers to the 
chyle of the higher animals, passes along the intestine, 
and the greater part of it, transuding through the walls of 
the alimentary canal, enters the blood, while the rest 
accumulates as dark coloured feces-in the hind gut, and 
Fie. 14.—Astacus fluviatilis,—The corpuscles of the blood (highly mag- 
nified). 7-8 show the changes undergone by a single corpuscle 
during a quarter of an hour; 9 and 10 are corpuscles killed by 
magenta, and having the nucleus deeply stained by the colouring 
matter. 2, nucleus. 
is eventually passed out of the body by the vent. The 
fecal matters are small in amount, and the strainer is 
so efficient that they rarely contain solid particles of 
sensible size. Sometimes, however, there are a good 
many minute fragments of vegetable tissue. 
The blood of which the nutritive elements of the food 
