CHAP, i The Cell 169 



the most noteworthy was Velten, who wrote in 1873-6. 

 He based his views on observation of the streaming move- 

 ments in the protoplasmic strands crossing the cell in 

 such plants as Tradescantia and Cucnrbita ; and taught 

 that the substance consists of numberless fine canals filled 

 with fluid, but shut off from the general cell-cavity. The 

 granules which previous observers had associated with the 

 fluid he attributed to the walls. In his first work he 

 denied that his system of canals was a spongy framework, 

 though later he to some extent modified his views on 

 this point. 



Among the animal physiologists many claimed to have 

 demonstrated a fibrillar structure in various animal cells. 

 Especially may be mentioned Remak in 1844, Max 

 Schulze in 1871, Flemming in 1882, and Schneider in 1891. 

 Various modes of arrangement of the fibrils were suggested, 

 Schneider holding it possible that the whole cell might be 

 only one long twisted filament. 



This theory, though in the main held through a long 

 series of years, soon underwent modification, and another 

 view was advanced side by side with it. This was the 

 reticular hypothesis, which owes much to the researches 

 of Fromman, carried on from 1865 to near the end of the 

 century. He formulated in 1867 his theory that proto- 

 plasm forms a network or reticulum of solid substance, 

 and that non-living liquid substance occupies the meshes. 

 The nodal points of the network give rise to the appear- 

 ance of the granules, or, at any rate, of some of them. The 

 theory was supported by a large number of observers, many 

 of whom advanced certain elaboration of Fromman's views. 

 According to some, the substance of the bars of the net- 

 work can be differentiated into a solid core, covered by 

 a softer substance. 



Fromman's theory was endorsed and elaborated with 

 great skill by Heitzmann in 1873, but while Fromman 



