ANATOMY OF THE EARTHWORM. 



149 



connected by a mesenteric membrane with the posterior 

 face of the partition. 



c. The external opening (Figs. 85, s, and 87), on the 

 ventral surface of the segment which contains the glandu- 

 lar portion of the organ. It is a very small aperture just 

 outside the inner bunch of setae. 



9. The reproductive organs. 



These, in their order of succession, are 



1. The seminal receptacles ; 2. The 

 testes; 3. The seminal vesicle; 4. The 

 vasa deferentia ; 5. The ovaries ; 

 6. The oviducts. 



a. The testes. Three pairs of large, 

 white, slightly vascular glands (Fig. 

 85, f), which project above and over- 

 lap the oesophagus in the ninth, tenth, 

 and eleventh segments. The two an- 



- ^ ^ M 



terior pouches unite with each other, 

 while the third is undivided. 



F:o. 86. Segmented organ of earthworm, 

 magnified twenty-five diameters, and freed from 

 the surrounding tissues. 



1. Central end. 2. Anterior margin. 3. Peri- 

 pheral end. 4- Posterior margin, r. Opening 

 into body cavity "ciliated funnel." s. Exter- 

 nal opening, a. Convoluted portion, b. Outer 

 fold. c. Inner fold. d. Muscular sac. 



(i.) Cut off a piece from one of the testes, and place a 

 drop of the white fluid which it contains under the micro- 

 scope. In it will be found mother cells and spermatic 

 filaments in all stages of development. 



b. The lower end of each testis is sharply constricted, 

 and united by a short neck to the seminal vesicle, a large, 



