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 spermathece. 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. 8. 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 spermathece of 
each come opposite the openings of the sperm-ducts of the other. 
The spermathece 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 
