32,1 THE BIOLOGICAL PROBLEM OF TO-DAY 



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ifcarbo - hydrates, water, salts, and they serve as 



jnaterjal for the nutrition and growth of the cell. 

 The former make up the living cell body (in the 

 narrow sense). They are able to multiply by growth 

 and division, and they are therefore the elementary 

 parts, units of life of lower rank, of which the cell, 

 a unit of higher rank, is composed. They are the 

 gemmules of Darwin, the physiological units of 

 Spencer, the bioblasts of Altmann, the pangenes of 

 De Vries, the plasomes of Wiesner, the idioblasts of 

 Hertwig, and the biophores of Weismann. 



The cells of every organic species possess a proper, 

 specific organisation, more or less complicated, and, 

 in correspondence with this, they are composed of 

 more or less numerous and varied organised 

 particles. 



The nucleus is a special organ of cells, which is 

 always present. It displays a collection of numerous, 

 peculiar, elementary living units, the idioblasts. 

 These show chemical, morphological, and functional 

 differences from the plasomes, the living units of 

 the protoplasm ; but perhaps the idioblasts, by ab- 

 sorption of different material, may transform them- 

 selves into the plasomes, just as these last, by a 

 similar process, may produce the plasma-products. 

 i Jn my view, the nucleus is the bearer of the idio- 

 y plasm or hereditary material, that is to say, of a 

 substance that is more stable than ^protoplasm, 

 and, because it is less subject to influences of the 

 outer world, it stamps its specific character upon 

 the organism. 1 



1 Notwithstanding the objections raised by Bergh, Verworn, 

 and Haacke, I abide by the supposition that the nucleus of repro- 



