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 faeces in the hind gut, and 



&1&*l 



FIG. 14. Astacm jturiatilis. The corpuscles of the blood (highly mag- 

 nified). 1-8 show the changes undergone by a single corpuscle 

 during a quarter of an hour ; and 10 are corpuscles killed by 

 magenta, and having the nucleus deeply stained by the colouring 

 matter, n, nucleus. 



is eventually passed out of the body by the vent. The 

 faBcal 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 



