CHAP. I The Cell 167 



by Cohn, Unger, De Bary, and others, is practically the 

 same thing as the ' sarcode ' of the animal physiologists, 

 though Unger had suggested it in 1855. The term proto- 

 plasm was originally used by Purkinje in 1840 to designate 

 the formative substance of the animal ovum. 



The development of knowledge of the structure and 

 behaviour of protoplasm bulked large in the researches of 

 the first twenty years of our period. It was studied alike 

 by botanists and zoologists, and as the animal and vegetable 

 substance was shown more and more clearly to be the 

 same, the researches calling for mention cannot be confined 

 to either. For our present purpose, however, it will be 

 convenient to put forward most prominently the work of 

 the botanists, though precedence must be given on many 

 points to zoological investigations. 



The first idea of the structure or constitution of proto- 

 plasm was that of a somewhat viscid, rather slimy fluid, 

 in which variable numbers of granules were present. This 

 was the idea which arose from microscopical examination 

 in days when technique was in its infancy and consequently 

 differentiation by means of staining was hardly possible. 

 Simple observation of such protoplasmic aggregations as 

 the plasmodia of Myxomycetes led to no further discovery. 

 This theory of protoplasm was held by Max Schulze him- 

 self, by Haeckel in 1862, and by Kiihne in 1864. These 

 observers saw the streaming movements which many cells 

 present, the flowing together of the pseudopodia of Amoeba, 

 the fusion of the masses of the plasmodium of the Myxo- 

 mycete, and the tendency of isolated portions of protoplasm 

 to become spherical. 



Very soon, however, the consideration of the various 

 complicated processes which even the simplest cell must 

 carry out led Briicke to realize how unsuitable for such 

 purposes must be a single viscid fluid. He suggested that 

 this simple appearance must cover some kind of organiza- 



