72 INVERTEBRATE ZOOLOGY 



with two pairs of funnel-shaped openings just posterior to the two 

 pairs of testes and in the same somites with them. At the hinder 

 margin of the twelfth somite the two tubes on each side unite 

 to form a single one, and the pair of tubes thus formed run back 

 to the fifteenth somite, where they open through the conspicu- 

 ous transverse slits already noticed, to the exterior. Look first 

 for the posterior portion of these tubes and trace them forward. 

 The spermatozoa pass from the testes, where they but partially 

 develop, into the sperm-sacs in which their development is com- 

 pleted and where they are grouped together in balls. From here 

 they pass, during pairing, into the sperm-ducts, and out of the 

 animal through the slit-like openings in the fifteenth somite. 



The female organs. 1. The spermathecae. These are two pairs 

 of spherical, white sacs beneath the sperm-sacs in the ninth and 

 tenth somites ; they are easily seen. 2. The ovaries. These are 

 a pair of extremely small organs lying near the median line and 

 attached to the anterior septum of the thirteenth somite near 

 the ventral body-wall; they will hardly be seen. 3. The ovi- 

 ducts. These are two minute, funnel-shaped tubes which extend 

 from immediately behind the ovaries through the septum to the 

 external opening in the next somite ; they will also hardly be 

 seen. 



Earthworms meet and pair in the night time during the 

 months of May and June. Two animals place themselves 

 alongside of each other in such a way that the spermathecae of 

 each come opposite the openings of the sperm-ducts of the other. 

 The spermathecse of each are then filled with spermatozoa from 

 the other animal. The worms then separate. Sometime later 

 the clitellum secretes a viscid fluid which hardens and forms a 

 tough cylindrical membrane around the body. The worm then 

 squirms backward, causing this membrane to pass forward toward 

 its head. As the membrane passes the fourteenth somite, eggs 

 are poured from the oviducts into the viscous mass which is held 

 between it and the body, and at the tenth and eleventh somites 



