'PHYSIOLOGICAL UNITS' 81 



as one which is entirely opposed to all positive evidence ; and can 

 only further regard the superstructure he has built upon it (as to 

 the function of the granular ' ids ' and all their imaginary myriads 

 of ' determinants,' composed in their turn of an endless variety of 

 'biophors') as based upon an extraordinai-y aggregate of assumptions 

 and hypotheses, destined to support his particular views concerning 

 heredity and evolution, but devoid of any independent support. 

 His knowledge is vast, and his absolute sincerity is undoubted ; 

 but his theories seem to have so thoroughly taken possession of 

 him that he is unable to resist attempting to explain in detail 

 things which it were wiser to regard as at present inexplicable. 



Let us get back now a little more into the region of facts and of 

 verifiable propositions, in regard to the all-important question as 

 to the functions of the nucleus and its relation to hereditary 

 phenomena. The interest here undoubtedly centres in the question 

 of the function that is to be attributed to the chromatin granules 

 (ids) which, when aggregated, go to form the chromosomes. 



An important point not yet referred to is this. The chromatin 

 is altogether differently arranged in different states of the cells. 

 In what has been termed the ' resting stage,' but which, as Herbert 

 Spencer says, would be better termed its ' growing stage,' the 

 chromatin is irregularly dispersed throughout the nucleus in the 

 form of a granular network ; and it is only when the time comes 

 for division of the cell to occur that, as one of the first of the very 

 complicated processes about to ensue, the chromatin granules 

 begin to aggregate so as to form the particular number of band 

 or rod-like ' chromosomes ' peculiar to the cells of the plant or 

 animal to which they belong. 



Subsequently, as it has been undoubtedly proved, each chromo- 

 some, in the process of division, becomes split longitudinally into 

 two equal portions ; the halves thus formed gradually separating 

 from one another, and the whole of each set later on becoming 

 aggregated so as to form one of the two daughter nuclei which now 

 find themselves in the divided cytoplasm of the original cell. At 

 this stage, the substance of the chromosomes again becomes dis- 

 tributed (by the separation of their component ids) so as to re-form 

 the nuclear network of chromatin granules, characterising the cell 

 during its growing stage. It is comm.only believed that the 

 chromatin of each chromosome preserves its identity during this 

 time, so that when the next division of the cell occurs, the chromo- 



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