A SQUID III 



radula. The latter organ, like the radula of snails, is used in chew- 

 ing the food ; examine its surface under a microscope and note the 

 calcareous teeth. 



Exercise 5. Make a drawing of the jaws. 

 Exercise 6. Make a drawing of several of the teeth of the radula. 



The Reproductive System: the Male. The principal genital 

 organs have already been observed. The single, median testis is a 

 large, flat organ, dorsal to the stomach pouch, in the hinder por- 

 tion of the visceral mass ; the genital artery joins it with the sur- 

 face of the stomach. The testis has no direct connection with the 

 vas deferens, but is surrounded by a thin, transparent membrane 

 within which it Ues as in a capsule, and into which the sperma- 

 tozoa escape. The vas deferens, which is also unpaired, commu- 

 nicates with this capsule. It is a long and much-twisted tube 

 with several wide, glandular regions, and lies, bound by connective 

 tissue into a compact mass, on the left side of the viscera. Take 

 the entire system out of the body, put it into water, loosen and 

 straighten out, as far as possible, the convolutions of the vas 

 deferens. Beginning with its hinder end we find first a narrow, 

 convoluted tube, and then follows a thicker, tubular portion, the 

 vesicula seminalis ; near the forward end of this portion is a 

 glandular body, the prostate gland, and a membranous sac ; a 

 long, straight, narrow portion comes next, which widens to form 

 the spermatophoric sac, within which the spermatophores are 

 formed ; then follows the tubular penis, which forms the for- 

 ward end of the tract and has already been observed lying in 

 the mantle cavity to the left of the rectum. 

 Exercise 7, a. Make a drawing of the male genital tract. 

 Exercise 7, b. Open the spermatophoric sac and look for spermato- 

 phores ; they are slender, white objects about half an inch long. 

 Mount several on a slide and make a drawing of one. 



The Female. The single ovary, like the testis, is a very large, 

 elongated gland occupying the hinder end of the visceral mass and 

 surrounded by a capsule. The oviduct communicates with this 

 capsule ; it passes forward along the left side of the visceral mass, 

 its walls becoming thickened in its course to form the oviducal 



