PLASM 



this name, especially the coarser froth-formation by 

 taking up water in the living matter and the invisible 

 hypothetical molecular structure. Both these must be 

 distinguished from the finer plasma-structure which is 

 visible under a powerful microscope; but the limit be- 

 tween them is difficult to determine. 



A second view of the finer structure of the plasm, 

 which had been greatly esteemed before the acceptance 

 of the froth theory, was formulated in 1875 by Carl 

 Frommann and Carl Heitzmann, and supported by 

 Leydig, Schwitz, and others. It puts another interpre- 

 tation on the net-like appearance of the microscopic 

 plasma-structure. It assumes that the plasma consists 

 of a skeleton of fine threads or fibrils combined in 

 the form of a net, and that these spread and cross in the 

 body of the cell which is filled with fluid. It is also 

 compared to a sponge, and is said to have a spongy 

 structure. We can artificially produce such a skeletal 

 structure by, for instance, causing coagulation in a thick 

 solution of glue or albumin by adding alcohol or chromic 

 acid. It is unquestionj,ble that there are these ' ' plasma- 

 skeletons" both in the nucleus and the body of the cell; 

 but they are generally (if not always) secondary prod- 

 ucts of organization in the elementary organism (or 

 cell - organs) , not primitive structures of its plasm. 

 Moreover, an optical transverse action of a froth- 

 structure or honeycomb, examined as a flat surface in 

 the microscope, shows the same configuration as a fine 

 skeleton. We can hardly see any difference between the 

 two. We cannot accept the skeletal formation as a 

 fundamental structure of the plasm. 



As we notice very fine threads in the plasm of many 

 cells, both in the caryoplasm of the nucleus and the 

 cytoplasm of the cell body, the cytologist Flemming, of 

 Kiel (1882), believed it was possible to discover them in 

 the plasm of all cells, and based on this his filar theory 



