CH. l] EARTHWORMS AND LEECHES 19 



the other, there is given out from the spermathecse of the 

 former a small quantity of mucus which hardens when 

 it reaches the air : a second portion of mucus containing 

 a group of spermatozoa is then emitted, this becomes 

 attached to the first mass, and with it forms a sperma- 

 tophore. The whole spermatophore is attached to the 

 body of the other worm close to the clitellum. When the 

 cocoon is made the spermatophores are rubbed off into 

 it as the animal withdraws itself. 



Light could probably be thrown on this matter by 

 some such experiments as follow: keep a number of 

 worms, each in a separate flower-pot, from infancy to 

 maturity ; kill l a few and examine the contents of their 

 spermathecse (it is conceivable that a worm may be able 

 to pass spermatozoa into its own spermathecse); allow 

 remainder to mate once, note if cocoons are deposited ; 

 kill some and examine contents of spermathecse; allow 

 rest to mate a second time, pairing some with their former 

 mates and others with different mates: kill all and 

 examine spermathecse. 



Recuperative powers. A worm if cut in two can under 

 favourable conditions recover, each portion ultimately 

 forming a complete worm. It is also possible to cause 

 the two severed portions to reunite, or to graft the head 

 portion of one worm on to the tail portion of another. 

 It is doubtful if under natural conditions such unions 

 of severed parts ever occur, but it is, at any rate, clear 

 that a worm can recover from the effects of wounds such 



1 The best way to kill worms is to plunge them for a moment in 

 boiling water. 



22 



