THE RENAL ORGAN. 83 
excrement of birds), a nitrogenous body analogous in 
some respects to uric acid, but less highly oxidated ; 
Fig. 18.—Astacus fluviatilis—A, the anterior part of the body, with 
the dorsal portion of the carapace removed to show the position of 
the green glands ; B, the same, with the left side of the carapace 
removed ; C, the green gland removed from the body (all x 2). 
ag, left anterior gastric muscle ; cv, circumcesophageal commis- 
sures; cs, cardiac portion of stomach; gg, green gland, exposed. 
in A on the left side by the removal of its sac; ima, inter- 
maxillary or cephalic apodeme ; as, cesophagus seen in transverse 
section in A, the stomach being removed ; s, sac of green gland ; 
x, bristle passed from the aperture in the basal joint of the antenna 
into the sac. 
and if this be the case, there can be little doubt that 
the green gland represents the kidney, and its secretion 
a2 
