262 PROTOPLASM 



way decisive in this matter, since tracts of the hardened alveolar 

 meshwork may quite well be isolated by teasing like fibrils in 

 certain places. I think that possibly special accumulations of the 

 granules in certain radial tracts may have been the cause of the 

 distinction laid down by Fol. 



Although I am willing to admit that the course of the 

 phenomena in the division of the nucleus and the cell har- 

 monises fairly well with the theory set up by van Beneden 

 and Boveri concerning the contractile nature and action 

 of the so-called fibrillse of the systems of rays, I am not . 

 inclined to consider my explanation of these processes as 

 improbable on that account. Apart from the structure of 

 the protoplasm not being, as a matter of fact, spongy or 

 fibrillar, a great number of important facts, which have been 

 detailed above, are in favour of it. It will be the subject of 

 a special investigation, based on the results of this work, to 

 discover whether there are not other points of view for 

 the processes occurring in cell and nuclear division, which 

 bring them into unison with my view of the significance of 

 the systems of rays. I entirely put aside for the present 

 the hypothetical, and in itself inexplicable, contractility of 

 the fibrils, since I shall treat of this point more in detail 

 later. On the other hand, I should like to point out that I 

 still consider the opinion developed by me at an earlier date 

 (1876) upon the forces that come into action in cell division 

 to be the probable one, at least in principle. 



6. The, HomogeTwous Protoplasm and the Alveolar Theory 



As we have frequently pointed out in the descriptive 

 portion of this work, the living protoplasm of certain 

 organisms occasionally appears entirely homogeneous and 

 structureless in parts, without even a trace of granular 

 contents. Gromia Dujardini in particular supplied us with 

 a good example of this, in its often very large pseudopodia. 

 The pseudopodia and the so-called ectoplasm of the fresh- 

 water Ehizopods, however, very often show the same condi- 

 tion, as has often been pointed out by earlier investigators. ' 



