168 The Anatomy of Plants BOOKII 



tion, which he conceived to be a solid cell-body, capable 

 of contractility and containing a fluid streaming through 

 it and carrying the granules. In other words, he held 

 protoplasm to have a firm contractile framework, steeped 

 in fluid. 



This position of Briicke's marked a great step in advance, 

 though his conception of the nature of the organization 

 was only rudimentary. It opened the way to more detailed 

 observation, which became more exact as experience was 

 gained of improved methods of technique. 



In 1863 Cienkowski, working on the plasmodium of the 

 Myxomycetes, suggested as its composition two fluids of 

 different densities, the one constituting the ground substance 

 being hyaline, and hardly more than semi-fluid, the other 

 more limpid, containing the granules in suspension. 



In 1864 De Bary suggested the view of a single semi- 

 fluid, or soft substance, contractile throughout, but ex- 

 hibiting local differences in its cohesiveness, fluidity and 

 mobility, all depending on variations in its content of 

 water. He was supported by Hanstein in 1870, and later 

 in 1880 and 1882. Hanstein distinguished in the proto- 

 plasm a hyaline ground substance hyaloplasm ; a more fluid 

 part the encliylema ; and the granules the microsomes. 



The single-fluid theory was held by Naegeli and Schwen- 

 dener in 1865 and indeed up to 1877. They considered 

 protoplasm to be mucilaginous in its consistency, and they 

 claimed for it some sort of organization, but they did not 

 accept Briicke's view of its structure. This theory of 

 a viscid fluid was shortly replaced by other views, but was 

 revived later by Schwarz, by Pfeffer, and in a modified 

 form by Berthold, and by Biitschli. To their hypotheses 

 reference will be made later. 



The view that protoplasm possesses a fibrillar structure 

 was the next to be advanced, and to find favour among 

 both animal and vegetable physiologists. Of the latter 



