No. 2.] STOLONIZATION IN AUTOLYTUS VARIANS. 289 



of the stolon and is effected by the contraction of the ruptured 

 tissue and a consequent drawing down of the ventral tissues of 

 the head. The shifting of the head tissues has a slightly rotat- 

 ing effect upon the anterior lateral tentacles so that the plane 

 of bifurcation, instead of being horizontal, is more vertical. At 

 the same time the tentacles are bent outward and become still 

 more thickened at the base. The posterior lateral tentacles 

 also increase in length and are extended forward some distance 

 beyond the margin of the head. As the spermatozoa which 

 are contained in segments i, 2, and 3 ripen, the walls of these 

 segments become somewhat distended and the outlines of the 

 segments remain quite definite. At the same time the walls 

 of the segments posterior to these more or less lose their out- 

 line, and it is with difficulty at times that the outlines of the 

 segments can be distinguished at all save by the location of 

 the parapodia. This condition marks the complete maturity 

 of the sexual products and hence also of the stolon, and may 

 appear shortly or some time after its separation from the chain. 

 Development of the Female Stolon. — The development of the 

 stolons of a female chain presents external changes very simi- 

 lar to the development of those comprising a male chain. Since 

 the female chains contain fewer stolons, the different stages in 

 the progress of development are not so well marked in the 

 same chain, and the chain usually is composed of successive 

 stolons which exhibit greater differences in age than in a male 

 chain ; the shortness of the chain being due, therefore, not to 

 an earlier separation of the stolon, but to a greater lapse of 

 time between the periods of stolon formation at the beginning 

 of the process. The early stages of the processes are identical 

 with those in the male chain, except for the bifurcation of the 

 anterior lateral tentacle and, in the older stolons, the appearance 

 of the dorsal tentacular cirri. The ventral tentacular cirri ap- 

 pear for the first time in a stolon which has reached a stage of 

 development corresponding to that of stolon 4, PI. XIII, Fig. 6. 

 In a stolon of this age the parapodia of the female stolon 

 are not unlike those of the male. At a somewhat later stage, 

 however, in a stolon corresponding in age to stolon 6, they 

 present an appearance quite different from those of the male 



