i64 PROTOPLASM 



comprehensive and very dogmatic assertions could only 

 be of harm to Heitzmann's theories, however much they 

 might be proved to be correct by later observations. 

 In the same way the attempt to eliminate the cell entirely 

 as an elementary unit in the building up of organisms, 

 could only increase the hostility of his opponents. Since 

 we must discuss more closely later on the theory of the 

 structure of protoplasm, developed by Heitzmann as far 

 back as 1873, and again, with greater detail, in 1883, 

 we may content ourselves in this place with these remarks. 



In 1875 Frommann also, in the investigation of the 

 blood corpuscles of Astacus, arrived in many points at the 

 same results as Heitzmann. Although Frommann certainly 

 observed fine networks in the living blood cells, even if 

 they are not very apparent in his figures, yet it appears to 

 me just as certain that the alterations he claims to have 

 seen in the two kinds of blood corpuscles — the gray ones 

 and the so-called granular cells — ^were nothing more than 

 post-mortem appearances. Thus I consider it beyond a 

 doubt that the blood corpuscles figured by him on Plate 

 XV., Figs. /, g, h, k, p, and Plate XVI., a-g and k-v, were 

 dead, and that therefore the vacuolisation of the yellow 

 granules of the granular cells, described already by Heitz- 

 mann, the formation of granules and networks from them, 

 and finally the alleged new formation of a nucleus in 

 the granular cells — that all this only depended on the 

 gradual death of the cells. In the ganglion cells also of 

 the crayfish Frommann was now able to clearly convince 

 himself of the existence of a reticular structure, and he 

 declared that the protoplasmic granules in them were only 

 the nodal points of the network. With regard to the rela- 

 tions between the framework of the nucleus and that of the 

 protoplasm, Frommann, as before, was essentially in agree- 

 ment with Heitzmann, since he energetically defended their 

 direct connection, just as Arnold also had done already. 



In the same year, 1873, in which Heitzmann described 

 the reticular structure in the protoplasm of Amcebse, the 

 botanist Velten, who also worked in Vienna, communicated 

 ±he results of his observations on the streaming protoplasm 



