76 THE STORY OF THE LIVING MACHINE. 



the problems connected with the study of life be- 

 came more simplified. In order to study the na- 

 ture 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 some- 

 what less confusing structures shown by individ- 

 ual cells. Even the simple cell has several sep- 

 arate parts capable of undergoing great modifica- 

 tions 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 prop- 

 erties of life. It moved, it could grow, and re- 

 produce itself, so that it was necessary only to 

 explain this substance and life would be explained, 

 (b) Nature of Protoplasm. What is this ma- 

 terial, 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 ap- 

 peared to have none. Its chief peculiarity, so 

 far as physical characters were concerned, was 

 a wonderful and never-ceasing activity. This 

 jellylike 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. 

 Chemical study of the same substance was of 

 no less interest than the microscopical study. 

 Of course it was no easy matter to collect this 

 protoplasm in sufficient quantity and pure enough 

 to make a careful analysis. The difficulties were 

 in time, however, overcome, and chemical study 

 showed protoplasm to be a proteid, related to 

 other proteids like albumen, but one which was 



