92 THE STORY OF LIFE'S MECHANISM. 



perties of living things irritability, contracti- 

 bility, assimilation, and reproduction. It was a 

 compound which seemingly deserved the name of 

 "physical basis of life," which was soon given to 

 it by Huxley. With this conception of proto- 

 plasm as the physical basis of life the problems 

 connected with the study of life became more 

 simplified. In order to study the nature of life 

 it was no longer necessary to study the confusing 

 mass of complex organs disclosed to us by 

 animals and plants, or even the somewhat less 

 confusing structures shown by individual cells. 

 Even the simple cell has several separate parts cap- 

 able of undergoing great modifications in different 

 types of animals. This confusion now appeared to 

 vanish, for only one thing was found to be alive, 

 and that was apparently very simple. But that 

 substance exhibited all the properties of life. It 

 moved, it could grow, and reproduce itself, so 

 that it was necessary only to explain this sub- 

 stance and life would be explained. 



(b) Nature of Protoplasm. What is this 

 material, protoplasm ? As disclosed by the early 

 microscope it appeared to be nothing more than 

 a simple mass of jelly, usually transparent, more 

 or less consistent, sometimes being quite fluid, 

 and at others more solid. Structure it appeared 

 to have none. Its chief peculiarity, so far as 

 physical characters were concerned, was a won- 

 derful and never-ceasing activity. This jelly- 

 like material appeared to be endowed with 

 wonderful powers, and yet neither physical nor 

 microscopical study revealed at first anything 

 more than a uniform homogeneous mass of jelly. 



