THE EARTHWORM AND ANNELIDS IN GENERAL 



183 



tubes, encircle both worms at the anterior and posterior edges of 

 the clitellar regions. These hold the worms firmly together and 

 may later aid in closing the ends of the cocoons. The slime tube 

 protects the co- 

 coon as it devel- 

 ops, and confines 

 the seminal fluid 

 and spermato- 

 phores. During 



copulation sperms are not exchanged between 

 the spermathecae of the two worms, but the 

 spermathecae of each are loaded from the 

 spermaducal pore of the other, or spermato- 

 phores formed in the spermathecae of one in- 

 dividual are attached to the skin of the other. 

 COCOONS. Cocoons are formed either 

 during copulation, or after the two worms 

 have separated. In the former case a band 

 is secreted about the clitellar region of one 

 worm and three or more opposite somites of 

 the other worm. At first the cocoons are 

 perfectly white (Fig. 94, B), but after deposi- FlG - 94- A, the an- 

 tion the exposure to the air changes them to 

 a yellow color. When copulation is completed, 

 the worms slowly withdraw backward from the 

 slime tube and cocoon. As the cocoon is 

 slipped over the head, its ends contract, 

 forming a turnip-shaped capsule, lying within 

 the slime tube (Fig. 94, B). The cocoon 

 after deposition contains, on an average, four 

 eggs, each of which has been penetrated by 

 from one to as many as nine spermatozoa. 

 The nucleus of a single spermatozoon unites 

 with the egg nucleus; the remaining sperma- 

 tozoa disintegrate (141, 142). 



tenor segments 

 of two copulat- 

 ing earthworms. 

 Slime tubes en- 

 circle the pair 

 from the 8th to 

 the 33d seg- 

 ment. B, co- 

 coon, freshly 

 deposited, of an 

 earthworm sur- 

 rounded by one 

 half of a slime 

 tube. (After 

 Foot in Journ- 

 Morph.) 



