288 



PROTOPLASM 



movement is hence also a chemical one. The movements 

 of an Amoeba which is flowing in a simple manner are 

 supposed to proceed as follows. At the anterior end of the 

 Amoeba, under the influence of the external medium, a 

 decomposition of the hyaline protoplasm is continually taking 

 place, a " disgregation," as he calls it ; in consequence 

 the hyaline protoplasm of the anterior end shrinks together 

 and becomes granular, being at the same time carried 

 towards the sides and finally towards the posterior extremity. 

 This granular shrunken protoplasm then gradually re-enters 

 the current, to become again restored, under the influence 

 of nourishment, to the former condition of hyaline proto- 

 plasm, its natural condition. During this process of recon- 

 stitution, however, it " stretches," and this stretching, which 

 has its seat chiefly at the anterior end of the Amoeba, where 

 the hyaline margin occurs, is the cause of the forward 

 movement and, of course, of the streaming generally. The 

 continual play of disgregation and reconstitution thus causes 

 the streaming of the Amoeba and similar protoplasmic 

 movements. Montgomery tries to extend this hypothesis to 

 explain also the contraction of muscles, but I will not 

 attempt to represent here his views with reference to this 

 point. 



Frommann has recently (1890) pronounced a very 

 shrewd critique upon Montgomery's hypothesis ; elsewhere I 

 have not seen it made the subject 'of earnest criticism, either 

 favourable or otherwise. I think that I may also omit any 

 discussion of it, the more so because, in my view, it is, in 

 the first place, altogether hypothetical, being in fact, as is 

 even asserted at the outset, not based at all upon physical 

 forces. Moreover, I am of opinion that, even if we accept 

 the postulates that are made, the regular protoplasmic 

 movements of Amoeba or of plant cells could never be 

 brought about by the alternate action of shrinking and 

 stretching which is asserted to occur. The fact, moreover, 

 that any explanation is lacking as to why the protoplasm 

 should, as a matter of fact, shrink after decomposition, and 

 should stretch when reconstituted, need not be brought for- 

 ward by me here as an objection. 



