278 General Biology 



opposite the 32nd (first clitellar) of its mate, then the thickened clitellum 

 forms a barrier past which no flow of seminal fluid can take place. 



"The long genital setae in the 'tubercula pubertatis' ( ) 



of the clitellum, and of segments 10 to 15, are probably used, the former 

 to liberate the cocoon from its seat of origin, and the latter series to 

 hold the cocoon off the ventral surface in the region of the oviducal 

 openings and those of the spermathecae, and thus allow ova and sper- 

 matophores to pass into the cocoon as it passes forward. These special- 

 ized setae replace those of ordinary form as the worm reaches maturity. 

 The eggs do not pass out of the oviduct till near the end of the act of 

 mating. Each of the two worms forms a cocoon, and slips out of the 

 cocoon backward, passing the cocoon forward over its head. The cocoon 

 being elastic closes its two open ends as soon as the body of the worm 

 is withdrawn, and becomes more or less lemon-shaped, its bulging center 

 being occupied by about four eggs, spermatozoa and albuminous material 

 produced by the so-called capsulogenous glands, which may be seen on 

 the ventral side of some of the segments in front of the clitellum. The 

 cocoons, at first white but soon becoming yellow, are left in the earth, 

 and as a rule only one of the contained eggs produces a young worm. 

 The size of the cocoons differs in the various species, those of L. 

 terrestris are from 6 to 8 mm. long by 4 to 6 mm. broad, of Eisenia. 

 foetida from 4 to 6 mm. long by 2 to 3 mm. broad. There is some doubt 

 as to the precise function of the spermathecae. It seems certain that 

 the spermatozoa contained in them, are derived from some other worm. 

 It is also the case that these organs are full of spermatozoa prior to 

 sexual union, and are empty subsequent to that act, at any rate when 

 cocoons are formed and eggs deposited. Worms have been observed to 

 separate without producing cocoons, and though perhaps in some in- 

 stances the separation may have been due to disturbance caused by 

 observation, yet there is reason to think that two unions are necessary, 

 one to fill the spermathecae, and a second to form cocoons. In such a 

 case it is probable that each worm acts as a carrier oi spermatozoa from 

 its first to its second mate, i. e., worm A gets its spremathecae filled by 

 the spermatozoa of B in the first union, and passes these spermatozoa 

 to C in the second. The actions are probably often reciprocal. Accord- 

 ing to Goehlich, while spermatozoa are flowing from one worm to the 

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

 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 spermatophore. 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 



