236 RECENT CYTOLOGY 



nuclear division, giving rise to the nuclear reticulum 

 in the daughter nucleus, are repeated in the reverse 

 order at the outset of the next division ; the same 

 processes are withdrawn into the same chromosomes, 

 and these shorten into structures identical with those 

 which passed into the nucleus at its first formation, 

 except that they have increased hi bulk during the 

 interval. 



Boveri, in fact, concludes that the separate chromo- 

 somes are to be looked upon as distinct individuals 

 almost as separate simple organisms which preserve 

 their individuality throughout the history of the cell, 

 and reproduce themselves, just as cells and nuclei do, 

 by a process of bipartition. As far as the chromo- 

 somes themselves are concerned, their typical or 

 resting form is that of the short simple rods seen in 

 mitosis. The branched anastomozing character seen 

 during the stage of the nuclear reticulum is associated 

 with the active co-operation of the chromosomes in the 

 physiological processes going forward within the 

 nucleus. For this reason the term ' resting stage ' 

 applied to this condition of the nucleus is a particularly 

 inappropriate one. 



Boveri illustrates the amount of credence which he 

 would attach to this theory of the individual persis- 

 tence of the chromosomes throughout the resting 

 condition of the nucleus, by means of the following 

 analogy : ' We make water from oxygen and hydrogen, 

 and from this water we can obtain oxygen and hydrogen 

 again in the same proportions. Just in the same way 

 as the chemist on the evidence of these facts regards 



