A HISTORY OF SCIENCE 



fibres penetrate the cell walls and connect adjoining 

 cells, so that the entire body is a reticulum. For the 

 moment there is no final decision between these op- 

 posing views. Professor Wilson of Columbia has sug- 

 gested that both may contain a measure of truth. 



Again, it is a question whether the finer granules 

 seen within the cell are or are not typical structures, 

 "capable of assimilation, growth, and division, and 

 hence to be regarded as elementary units of structure 

 standing between the cell and the ultimate molecules 

 of living matter." The more philosophical thinkers, 

 like Spencer, Darwin, Haeckel, Michael Foster, August 

 Weismann, and many others, believe that such "in- 

 termediate units must exist, whether or not the mi- 

 croscope reveals them to view. Weismann, who has 

 most fully elaborated a hypothetical scheme of the 

 relations of the intracellular units, identifies the larger 

 of these units not with the ordinary granules of the 

 cell, but with a remarkable structure called chromatin, 

 which becomes aggregated within the cell nucleus at 

 the time of cellular division a structure which divides 

 into definite parts and goes through some most sug- 

 gestive manoeuvres in the process of cell multiplica- 

 tion. All these are puzzling structures; and there is 

 another minute body within the cell, called the centro- 

 some, that is quite as much so. This structure, dis- 

 covered by Van Beneden, has been regarded as essential 

 to cell division, yet some recent botanical studies seem 

 to show that sometimes it is altogether wanting in a 

 dividing cell. 



In a word, the architecture of the cell has been 

 shown by modern researches to be wonderfully com- 



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