86 



THE STORY OF THE LIVING MACHINE. 



lations in regard to this protoplasm. Its lack of 

 homogeneity became more evident, until there has 

 finally been disclosed to us the significant fact 

 that protoplasm is to be regarded as a substance 

 not only of chemical but also of high mechanical 

 complexity. The idea of this material as a simple 

 homogeneous compound or as a mixture of such 

 compounds is absolutely fallacious. Protoplasm 

 is to-day known to be made up of parts harmoni- 

 ously adapted to each other in such a way as to 

 form an extraordinarily intricate machine ; and the 

 microscopist of to-day recognizes clearly that the 



activities of this 

 material must be 

 regarded as the 

 result of the 

 machinery which 

 makes up pro- 

 toplasm rather 

 than as the sim- 

 ple result of its 

 chemical com- 

 position. Proto- 

 plasm is a ma- 

 chine and not a 

 chemical com- 

 pound. 



Structure of 

 Protoplasm. 

 The structure of 



brane; d, nuclear reticulum; e, chro- protoplasm isnot 

 matin reticulum ; f, nucleolus ; g, cen- yet thoroughly 



understood by 

 scientists, but a 

 few general facts are known beyond question. It 

 is thought, in the first place, that it consists of 



FIG. 23. A cell as it appears to the modern 

 microscope, tf, protoplasmic reticulum ; 

 b, liquid in its meshes ; c, nuclear mem- 



