B. Summary of Divergent Views 



1. The Theory of the Fibrillar Structure of Protoplasm 



Ix opposition to the theory of the reticular framework 

 of protoplasm, some investigators still hold fast to the con- 

 ception which was so prevalent at an earlier period of the 

 investigations, namely, that we have to deal with fibrils 

 which are isolated, or at least only occasionally connected 

 secondarily, in the intervening matrix of protoplasm. In 

 fact, we have seen already that not a few authors of the 

 works described briefly in the foregoing section speak of 

 fibrils of protoplasm, though at the same time admitting that 

 these fibrils anastomose as a rule in a net-like manner, even 

 if they occasionally occur isolated. 



The assumption of a fibrillar structure in protoplasm ob- 

 tained the most definite support in Flemming's book of 1882.! 

 The earlierworks of Frommann, Arnold (1879) and Schleicher' 

 (1879, upon the composition of the protoplasm of cartilage 

 cells), can also be regarded as to a certain extent precursors 

 of such a conception. Schleicher especially gave a most 

 definite denial to the alleged existence of reticular structures 

 in the protoplasm of cartilage cells, in opposition to Heitz- 

 mann and others, but frequently observed, on the contrary, 

 isolated filaments in their living protoplasm. 



It cannot indeed be asserted that Flemming affirms 

 definitely the fibrillar nature of protoplasm ; his standpoint is 

 rather a sceptical one towards Heitzmann, Klein, and others. 

 Thus he admits a net-like connection of the filaments of the 

 protoplasm as " fully possible for many objects, but can, 

 however, find no certainty for the fact" (p. 58). The 



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