194 PROTOPLASM 



tide has the power of " binding " two neighbouring particles ; 

 then filaments are formed. If, however, a particle is able 

 to bind three others, networks arise. As examples of such 

 active structures, he considers those of the nuclei and the 

 fine protoplasmic structures, which he himself described in 

 the red blood corpuscles of Amphibia (see above, pp. 130 and 

 173). 



I think I scarcely need point out that in these specula- 

 tions Pfitzner did not go upon actual physical grounds, but 

 that the forces of attraction and repulsion brought into play 

 were specially invented for this service. One point, how- 

 ever, I should like to emphasise particularly. In Pfitzner's 

 passive reticular structures the framework is of course the 

 true protoplasmic substance become reticular from the 

 formation of vacuoles. But in active structures, on the 

 other hand, the contents of the network, or the intervening 

 matrix, would be the true original protoplasm. My view, 

 on the contrary, regards both structures as essentially the 

 same. 



Brass (1883-85) is also of the opinion that the reticular 

 structures occasionally observed by him were formed by a 

 serial arrangement of the granules. Kultschitzky (1883) 

 had the same idea with regard to the striations in the 

 sensory cells of Gaudry's corpuscles, and Schiefferdecker 

 (1887) with regard to the fibrillar structure of ganglion 

 cells. Moreover, Vejdowsky (1888) drew from his inves- 

 tigations on the formation and development of the eggs of 

 Rhynclielmis, the conclusion that protoplasm is originally 

 quite homogeneous and structureless (p. 19); that then 

 very minute granules make their appearance in it, which 

 " begin to group " themselves ; " rather later there arise 

 from these granules, especially in the neighbourhood of 

 the nucleus, filaments running irregularly and crossing 

 repeatedly " " thus arises the reticulum of the Cytoplasma " 

 (p. 20). In the course of the segmentation of the egg also, 

 Vejdowsky believes he has frequently seen reticular proto- 

 plasm becoming homogeneous, and differentiating again 

 into structured. He therefore sees in the structures of 

 protoplasm and cells, "products of the processes of nutri- 



