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 seoTnent which contains the o^landu- 

 lar pori;ion of the organ. It is a very small apertm'e just 

 outside the inner bunch of setae. 



9. The reproductive organs. 



These, in their order of succession, are — 



1. The seminal receptacles ; 2. The 3 



testes; 3. The seminal vesicle; 4. The h 



vasa deferentia ; 5. The ovanes ; 

 6. The oviducts. 



a. The testes. Three pairs of large, 

 white, slightly vascular glands (Fig. 

 85, /), which project above and over- 

 lap the oesophagus in the ninth, tenth, 

 and eleventh segments. The two an- 

 terior pouches unite with each other, ^ 

 while the third is undivided. 



F:o. 86. — Segmental organ of earthworm, 

 magnified twenty-five diameters, and freed from 

 the surrounding tissues. 



1. Central end. 2. Anterior mai^in. 3. Peri- 

 pheral end. 4- Posterior margin, r. Opening 

 into body cavity — "<;iliated 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 stiiges of development. 



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

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



