16 



EARTHWORMS AND LEECHES 



[CH. I 



rest for a longer or shorter period in small sacs situated 

 upon the sides of the ovi- 

 ducts. In the mating of 

 such species as pair above 

 ground, two worms from ad- 

 jacent burrows, each retain- 

 ing a firm hold in its own 

 burrow by means of its flat- 

 tened tail, apply their ventral 

 surfaces to one another so as 

 to overlap for about a third 

 of the length of the body. 

 The head of each worm points 

 toward the tail of the other. 

 The clitellum of each secretes 

 a band of mucus which binds 

 the two worms firmly together, 

 so firmly, indeed, as to cause Fi ?;4l , 

 two well-marked constric- 

 tions, while a slimy covering, 

 the slime-tube, surrounds the 

 two worms from the 8th to the 

 33rd segments. The seminal 

 fluid, containing spermatozoa 

 and spermatophores, flows 

 within the slime-tube, and, The Roman figures refer to the 



during sexual union, in the number of the 8egment8 ' 

 early stages of the formation of the cocoons spermatophores 

 cover the dorsal and lateral surfaces of segments 9, 10 

 and 11 of each worm and are packed between the two 



Lumbricus terrestris. Slightly 

 magnified. From Hatschek and 

 Cori. 



gus. 4. Crop. 5. Muscular 

 gizzard. 6. Intestine. 7. Ne- 

 phridia (the reference lines do 

 not quite reach the nephridia). 

 8. Septa. 9. Dorsal blood vessel. 

 10. Hearts. 11. Spermathecee. 

 12. Vesiculse seminales. 



