218 ELEMENTARY BIOLOGY. [CHAP. 



diverge, a short transverse branch uniting the 

 two anteriorly. The vas deferens arises a little in 

 front of the middle of each testis and passes 

 without convolution towards the genital opening. 

 Its distal half is dilated. 



c. Tease out a bit of the testis in water, and examine 

 with \ obj. : it will be seen to be composed of 

 glandular tubes terminating in grape-like saccula- 

 tions. In it or in the vas deferens ripe spermatozoa 

 may be found : they are motionless, discoidal, and 

 provided with long radiating processes. Stain with 

 eosin, and note 



a. The annulate corpuscle ; a transparent ring, lying 

 within the middle of cell body. 



y8. The oval corpuscle ; a granular mass, lying to one 

 side of a. 



In the Lobster the spermatozoa are also motion- 

 less ; each consists of an elongated cell, from one 

 end of which three rigid pointed processes radiate. 



2. The female organs. 



a. The ovary; in shape very similar to the testis of 

 the male, being bilobed anteriorly. 



b. The oviducts ; two short ducts which, like the vasa 

 deferentia of the male, are directly continuous with 

 the genital gland. They can be at once seen on dis- 

 placing the anti-penultimate walking legs to one 

 side (Sect. A. c. y). 



A supernumerary oviduct, opening upon the 

 second ambulatory appendage, may be very rarely 

 present (cf. p. 186). 



