MULTIPLE CHROMOSOMES 577 



well be that in the latter instance, which concerns questions of 

 fiber insertion or other variation between homologous chromo- 

 somes, the simple method of segregation and chance recombina- 

 tion obtains, while in H. viridis, where non-homologous chromo- 

 somes are involved, another mechanism is operative. Genetical 

 experiments will shed some light on these difficulties and it is 

 hoped that these may be completed before long. 



7. Chromosome individuality 



As has been stated elsewhere in this paper, the circumstances 

 relating to the multiple chromosomes are strong proofs of the 

 theory of chromosome individuality, as indeed are all facts indi- 

 cating order and definiteness in form and beha^dor. So far as 

 I can see there is no half way gi'ound between the assumption 

 that the chromosomes are definite, self-perpetuating organic 

 structures and the other which presents them as mere incidental 

 products of cellular action. According to one view individual 

 chromosomes are descendants of like elements and possess cer- 

 tain qualities and behavior because of their material descent, 

 the visible mechanism for which is the process of mitosis: ac- 

 cording to the other any similarities that may exist in the com- 

 plexes are the result of chance aggregations of non-specific ma- 

 terials. It is a choice between organization and non-organiza- 

 tion in the last analysis, at least in terms of cellular structures. 

 To attempt the substitution of a conception of molecular or- 

 ganization, which is beyond the experience of the biologist and 

 which exceeds the present powers of the chemist to analyse, is 

 to cast aside all hope of solving the problem of cellular action, 

 because it is necessary to understand, not only the physical and 

 chemical phenomena involved, but also their different forms in 

 the various parts of the cell. It is readily admitted that these 

 are not the same in the nucleus and in the cytosome, but some 

 hesitate to recognize differences between parts of the nucleus, 

 and more are disinclined to grant specific activities to the 

 chromosomes. 



Since it is not possible to observe directly the action of the 

 chromosome we are obliged to make use of indirect evidence, 



