396 TRANSACTIONS LIVERFOOL BIOLOGICAL SOCIETY. 
The secretion of the digestive gland is capable, 
therefore, of acting upon proteids, starch and fats, or, in 
other words, it contains proteolytic, amylolytic and 
lipolytic ferments, like the pancreatic juice of vertebrates. 
The action of these ferments is to convert colloid materials 
like starch and proteid into the diffusible materials, sugar 
and peptone, which are eventually absorbed; and the 
intestine must be considered as the place where this 
absorption is going on, the descending lmb from the 
stomach being probably the main portion concerned. 
The intestine may be divided into three sections, 
which are of practically the same length: (1) the 
descending portion (fig. 36, Al. ¢. 3); (2) the ascending 
portion (Ad. c. 4); and (3) the rectum (Al. ¢. 9). 
(1) The descending limb of the intestine arises from 
the stomach, not posteriorly, but ventrally, at almost the 
middle of its length, and passes anteriorly and downwards 
from the stomach through the digestive gland to the 
reproductive region of the visceral mass (fig. 1). At 
ihe level of the foot this portion of the intestine lies 
amidst the tubules of the gonad, in the median line, very 
near to the surface of the visceral mass lying against the 
adductor muscle. From this point it curves forwards 
towards the free margin of the visceral mass, and in 
P. marimus extends down to the extreme end of the latter, 
where it bends suddenly and returns as the (2) ascending 
limb. This hes close to the adductor surface all the 
way and at first in the median line, but when the point is 
reached where the descending portion comes near to the 
adductor, the ascending portion is displaced and les to 
the right of it, so that it eventually plunges into the 
digestive gland on the right side, and hes near the surface 
on the right side close to the adductor muscle. It passes 
up to the dorsal surface of the gland, where it lies in the 
