24 



ant than the changes in the protoplasmic cup. We shall there- 

 fore follow the capsular changes very carefully. The first 

 change is the out pushing of the outer cavity of the inner 

 tubule. CoBjpare Pig. 61 with 67. Here it is evident that 

 the wall of the outer cavity of the inner tuhule has been 

 everted, while the wall of the inner cavity (Pig. 61 » i.t.o.) 

 has been stretched. It is difficult to see Just what change 

 has taken place at this time in the central body. In some 

 instances it appeared that it had been lengthed, and in some 

 specimens I thought the end of it could be seen at the summit 

 of the out pushed portion. It may be that the lengthening 

 of this body is the force that turns this distal cavity inside 

 out. 



In the next step of the capsular inversion the thick cov- 

 ering of the out pushed part shown in Pig. 67 becomes turned 

 out lateraly so as to form a collar (Pig. 68, r.) and the inner 

 tubule becomes father everted. The collar formed at this 

 stage persists unchanged throughout all the further modifica- 

 tions of the capsule. The central body may now become great- 

 ly increased in length so that it projects beyond the out 

 turned part of the inner tubule (Pig. 69, c.b. also Pigs. 

 70 to 72). Prom this stage on to the completion of the ever- 

 sion there is little further Increase in the length of this 

 axis. The everted portion of the inner tubule however swells 

 out more and more (Pigs. 77 to 79). The transition from the 

 condition shown in Pigs. 71 and 76 to that in Pigs. 77 to 79 

 is brought about by a further everslon of the inner tubule. 

 The part of the inner tubule involved in this second definite 



