()1?GANS OF CAMPAMTLARIA GENICULATA. 63 



palo, nncloatotl, round cells, exactly lil<c the spermatic germ- 

 cells ol other animals. In the globules placed higher up 

 these cells are seen with a paler, almost inapparent nucleus, 

 the outline of the cell has lost its uniform rotundity, and 

 begins to elongate on one side into a short process. As the 

 development proceeds, the nucleus disappears altogether, the 

 cell is somewhat smaller and the piocess longer, and fine as a 

 hair, exhibiting a very peculiar slow movement, not unlike 

 that of t!ie motile cilium of a Eucjlena^ in consequence of 

 which the entire cell acquires a quivering motion sometimes 

 amounting to an inconsiderable change of place. This mo- 

 tion, however, is quite different fiom and slower than that 

 of a mature spermatozoid. The cell is thrown from side to 

 side, frequently appearing as if it was supported upon the 

 process. 



Other forms of development are commonly associated with 

 the above in the same globule. Every cell has this flexible 

 process, by the movement of which they are thrown from side 

 to side ; but besides this they have also a greater or less 

 number of rigid, motionless, less delicate processes, varying in 

 number from 1 to 5, and appearing to arise in succession, and 

 by which these forms are rendered like the stellate cells of 

 KoUiker, and which are a common stage of development of 

 the spermatozoids in the Crustacea. But the latter have no 

 motile appendage, and are always quite motionless. 



1 am not aware of any observation of movements at such an 

 early stage of development of spermatozoids. 



With respect to tlie successive formation of the individual 

 processes, I have not been able to observe anything certain ; 

 but it appears to me probable that the motile process after a 

 time becomes immotile, and that a new motile process com- 

 monly makes its appearance at the opposite point, which 

 again passes into the motionless state, and so on. 



It is only rarely that cells occuned without a motile process. 

 The greatest number of rigid processes on a single cell, that 

 fell under my observation, was four. 



A necessary precaution to be taken, in order that the motion 

 of the delicate process should be observed, is the avoiding too 

 strong and too long-continued pressure upon the capsule with 

 the view of rupturing it. The best way of proceeding is to 

 provide that, besides the capsule, there should be a somewhat 

 more resistant object — a portion of vegetable tissue or of the 

 polypidom itself — and then, whilst looking through the micro- 

 scope, to make gradual pressure upon the covering glass until 

 the capsule is ruptured. If the pressure is now omitted, the 

 glass usually rises again a little, affording the requisite space 

 beneath it. 



