ANNELIDA OR ANNULATA 



"3 



8th to the 37th somite. Two parallel 

 lines extend posteriorly from the vasa defe- 

 rentia to the clitellum, forming primitive 

 channels for the passage of seminal fluid. 

 Within the slime-tube the seminal fluid 

 flows, containing free spermatozoa and 

 spermatophores. The spermatophores 

 are deposited in the seminal receptacles of 

 the other worm and the slime-tube is 

 soon left. 



Fertilization. — Later on at the appear- 

 ance of the capsule or cocoon, formed by 

 capsulogenous glands in the clitellar 

 region, the 4-6 mature eggs are picked up 

 at the egg-sacs opening at the oviducal 

 apertures in the 14th somite; and the 

 sperms that were stored in the receptacles 

 are secured at their openings between the 

 9th and loth and the loth and nth 

 somites. Fertilization is effected in the 

 cocoon at the time it slips off over the 

 head, and since the sperms are from an- 

 other animal, self-fertilization is pre- 

 vented. In Lumbricus comtnmiis, two 

 embryos are produced as a rule, in many 

 cases arising as twins from a single ovum. 

 Foot found (1898) that the total number 

 of eggs in 100 cocoons was 399, about 4 

 to a cocoon. Isolated worms deposit 

 cocoons for weeks. 



The observations of Foot and Wilson 

 have been to some extent contradicted by 

 Grove and Cowley (1926), who found in 

 Eisenia foetida that cocoon formation 

 does not take place while the worms are 

 still united by the conjugation slime tube.^ 



2 Grove, A. J., and Cowley, L. F. 1926. On 

 the reproductive processes of the brandling worm, 

 Eisenia foetida (Sav.). Quart. Jour. Microsc. Sci., 

 70 (4), 559-581- 



KL A> 



Fig. 49. Sperm transfer 

 in Lumbricus terrestris, 

 (Drawn by W. J. Moore.) 



