CHAPTER XII 



PROTOPLASM, THE PHYSICAL BASIS OF LIFE 



THE recognition of the role that protoplasm plays in the 

 living world was so far-reaching in its results that we take 

 up for separate consideration the history of its discoveiy. Al- 

 though it is not yet fifty years since Max Schultze established 

 the protoplasm doctrine, it has already had the greatest 

 influence upon the progress of biology. To the consideration 

 of protoplasm in the previous chapter should be added an 

 account of the conditions of its discovery, and of the person- 

 ality and views of the men whose privilege it was to bring 

 the protoplasm idea to its logical conclusion. Before doing 

 so, however, we shall look at the nature of protoplasm 

 itself. 



Protoplasm. This substance, which is the seat .of all 

 vital activity, was designated by Huxley " the physical basis 

 of life," a graphic expression which brings before the mind the 

 central fact that life is manifested in a material substratum 

 by which it is conditioned. All that biologists have been able 

 to discover regarding life has been derived from the observa- 

 tion of that material substratum. It is not difficult, with the 

 help of a microscope, to get a view of protoplasmic activity, 

 and that which was so laboriously made known about 1860 

 is now shown annually to students beginning biology. 



Inasmuch as all living organisms contain protoplasm, 

 one has a wide range of choice in selecting the plant or the 

 animal upon which to make observations. 



We may, for illustration, take one of the simplest of animal 

 organisms, the amoeba, and place it under the high powers 



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