172 WORMS. 



two ciliated funnels, which collect spermatozoa in seg- 

 ments 10 and II, and soon unite in one duct. 



{b) The Female Organs consist of two ovaries, and two 

 oviducts each of which has a side receptacle for the eggs. 



(i) The two ovaries are small bodies situated near the 

 nerve-cord on the septum between segments 12-13. Each 

 is pear-shaped, the stalk of the pear being a string of ripe 

 ova. They are more likely to be seen than the testes. 



(2) The two oviducts open internally on the anterior face 

 of the septum between 13-14, and externally on the 

 ventral surface of segment 14. Into the wide ciliated in- 

 ternal mouths, which lie opposite the ovaries, the ripe eggs 

 pass. 



(3) The egg-sac or receptaculum ovorum, near the internal 

 mouth of each oviduct, is a posterior diverticulum of the 

 septum between segments 13-14. Within it a few mature 

 ova are stored. 



{c) Two pairs of spermathecae receive spermatozoa from 

 another earthworm, and liberate them so that they fertilise 

 the eggs of this one. They are white globular sacs, opening 

 in the grooves between segments 9-10 and lo-ii. Accord- 

 ing to some, these spermathecae not only receive and store 

 spermatozoa, but make them into packets or spermatophores. 

 Others say that the glands of the clitellum make these 

 packets. At any rate minute thread-like packets of sperma- 

 tozoa are formed, and a pair of them may often be seen ad- 

 hering to the skin of the earthworm about the saddle region. 



When two worms unite sexually they lie apposed in 

 opposite directions, the head of the one towards the tail of 

 the other. What happens is that spermatozoa of the one 

 pass into the spermathecae of the other. 



When the eggs of an earthworm are liberated they are 

 surrounded by a sheath of gelatinous stuff s'ecreted by the 

 saddle. As this is peeled off towards the head a sper- 

 matophore is also enclosed. The packet bursts in the egg- 

 capsule, and there fertilisation at length occurs. 



Development of the Earthworm. 



The various species of Lumbricus deposit their ova within 

 cocoons, the substance for which is secreted by the saddle. 



