39 



(2) En Sepia a branch from the gastric ganglion may 

 be followed up the wall of the intestine to its tip. At the 

 point where the ink duct joins the intestine this nerve 

 gives off a very fine branch which runs down the wall of 

 the duct and gland to the posterior end. This nerve 

 regulates the secretion of pigment, while the visceral 

 nerve branches control the muscular contraction of the 

 ink sac (Girod). 



The ink sac has rather an elaborate vascular system. 

 The abdominal aorta, running up from the heart to the 

 intestine, gives off a vessel to the ink sac (PI. VI, fig. 49, 

 I.S.A.). This enters at its base, first giving off at each 

 side a spirally curved vessel to the corresponding lobe of 

 the pancreas (fig. 32, P. A.). Then it divides into four 

 vessels, which become embedded in the wall of the ink 

 sac and send branches to the internal glandular 

 trabeculae. The ink duct also receives a small artery 

 from the terminal portion of the intestinal vessel. 



The vein runs from the sac into the posterior part of 

 the anterior vena cava (posterior hepatic vein). It is 

 formed by the union of two vessels which run one on 

 either side of the ink sac and unite at its base. On their 

 way these receive branches from the sac, and much longer 

 ones from the liver and pancreas (fig. 32, I.S.V.). 



Structure. — Cutting a sagittal section of the gland, 

 the following portions may be seen: — (1) The basal 

 glandular part (PI. IV, fig. 26, I. gld.) ; (2) the reservoir 

 above this (fig. 26, Res.) ; and (3) the duct, of about equal 

 length with the gland. Its terminal portion lies external 

 to the visceral envelope (fig. 32), and bears two internal 

 valves, just near the anterior end. 



The glandular part, after being well washed, will be 

 seen to consist of numerous trabeculae, which branch and 

 run into one another (fig. 26, tr.). These are membranous, 



