76 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



units of the nucleus These facts point 



unmistakably to the conclusion that these granules are 

 perhaps to be regarded as independent morphological 

 elements of a lower grade than the chromosome. 



. The smallest chromatin grains may successively 

 group themselves in larger and larger combinations of 



which the final term is chromosome 



Whether these combinations are to be regarded as in- 

 dividuals is a question which can only lead to a barren 

 play of words. Are these the ultimate dividing units as 

 Braur suggests? When all these facts are placed in con- 

 nection we find it difficult to escape the conclusion that 

 no definite line can be drawn between the cytoplasmic 

 granules at one extreme and the chromatin granules at 

 the other. And in as much as the latter are certainly 

 capable of growth and division, we cannot deny the pos- 

 sibilities that the former may themselves have or arise 

 from elements having like power. 



"A fragment of a cell deprived of its nucleus may live 

 for a considerable time and manifest the power of co- 

 ordinated movement without perceptible impairment. 

 Such a mass of protoplasm is, however, devoid of the 

 powers of assimilation, growth and repair, and sooner or 



later dies For these and many other 



reasons to be discussed hereafter the nucleus is generally 

 regarded as the controlling center of cell-activity and 

 hence a primary factor in growth development and the 

 transmission of specific qualities from cell to cell and so 

 from one generation to another." 



In its simplest form the centrosome is a single minute 

 granule, which may, however, become double or triple as 

 in the white blood cells of the body, connective tissue 



cells or epithelial cells or skin cells During 



the formation of the spermatozoon, the centrosome 



