i893. ARTIFICIAL PROTOPLASM. 35 



A large part of the remainder of the book is occupied by a dis- 

 •cussion of various existing theories of the structure of protoplasm, 

 and it concludes by foreshadowing possible explanations of various 

 phenomena like the streaming movements in plant cells, and muscular 

 contraction, upon the basis of his interpretation of the structure of 

 protoplasm. 



Put generally, Professor Btitschli's results are these : Protoplasm is 

 itself a special chemical substance, the seat of many chemical changes. 

 But it is also a physical substance, with definite physical texture, 

 and obeying definite physical laws. It is possible to construct foams 

 •of different chemical nature but with similar physical properties. 

 These foams show that protoplasm is composed not of a network 

 containing sap and granules, but of a series of delicate bubbles obey- 

 ing the physical conditions that rule bubble structures. The contents 

 of the bubbles are some kind of fluid — a fluid which can be replaced 

 by glycerine and other reagents. Many of the familiar features in 





^_> , 



*~'\- 



- f -'^ ' -^ 



Fig. 5.— Protoplasm of. 4 »ia-6rt (Coc/i/io/iorf/KW!?) Fig. 6.— Nucleus with part of surrounding plasma 



actinophora. from gangliar cell of os. 



the microscopic appearance of protoplasm — features like the network, 

 the granular and fibrillar appearances, the striated alveolar layers, 

 are the optical expression of this frothy structure. 



Streaming movements, changes of shape, progression through 

 fluids, are physical conditions. In artificial froths they can be referred 

 easily to differences in surface tension inside the froth and between 

 the froth and the surrounding fluid. The more complex chemical 

 conditions and the active chemical changes in protoplasm render it 

 highly probable that complicated changes of tensions within and 

 without the cell are constantly being produced, and so there is to be 

 expected a more lifely manifestation of the movements of streaming, 

 of change of position and change of shape, which are actually present 

 in the relatively simple artificial froths. A combination of fuller 

 knowledge of the chemistry of protoplasm, combined with this fuller 

 knowledge of its physical structure, would go far, if not the whole way, 

 to an understanding of life. 



D2 



