320 H. M. BERNARD. 



but we gather from the retina, in Avliich the majority of 

 nuclei have no granular cytoplasm, that the nuclear prickles 

 run directly from nucleus to nucleus ; whereas, on Heitzmann's 

 system, each nucleus is connected by its prickles with a 

 surrounding mass of cytoplasm, and each of these surround- 

 ing masses of cytoplasm is connected by its prickles with 

 those that are adjacent to it. It is clear that a protomitomic 

 system such as we have described, in which all the nuclei are 

 joined by connecting filaments which would run through 

 any cytoplasm associated witli the nuclei and themselves 

 form the basis of the intercellular bridges, would fulfil all 

 the essential requirements of Heitzmann's description of the 

 finer structure of protoplasm. 



And here I would call attention to the fact that, according 

 to Professor Macfarlane, in the case of plants also nearly all 

 the separate elements for the demonstration of similar 

 fibrillar continuity underlying the protoplasm are at hand. 

 Professor Macfarlane^ has recently emphasised them and 

 indicated the direction in which they all point. All that is 

 now required is the actual demonstration that the phenomena 

 are all parts of one and the same system. This linking 

 together of the chain cannot be long in forthcoming, since 

 it has now been definitely accomplished for animal tissues, 

 i. e. for the retina in the first instance. ^Jliat it is a universal 

 phenomenon we shall proceed to show. 



But we have by no means exhausted the evidence to be 

 gathered from the retina for the existence of this protomitomic 

 system, nor have we attempted to correlate it Avith any of the 

 known functions of the retina in order to see whether any 

 light can be obtained as to its physiological importance. 



We naturally proceed, then, to see if it is possible to make 

 out the connections of the protomitomic system proximal ly 

 Avith the nerves and distally with the rods. It is obvious 

 that, if such a direct connection exist, we have the link, so 

 long looked for in vain, between the nerve-strands, on the one 



^ ' Contribulions from tl)C Botanical Laboratory of Pennsylvania Univer- 

 sity,' vol. ii, Part 11 (1901), p. 187. 



