MULTIPLE CHROMOSOMES 579 



beyond question; pro\dsion for the perpetuation of the organic 

 unity of the individual chi'omosomes is found in the process of 

 nriitosis; the actual direct result of its operation appears in the 

 uniform conditions of the complex in the individual animal; the 

 extension of this beyond the organism to the group and the 

 means for it in the phenomena of maturation and fertilization 

 are easily established by observation; the age old existence of all 

 these circumstances is revealed by the near approach to uni- 

 formity in the chromosome complex of the rnultitude of species 

 of unnumbered individuals constituting a family. And yet, in the 

 face of this overwhelnung mass of evidence indicative of order, 

 system and specific chromosome organization, some conceive only 

 the action of ordinary chemical forces, or the chance associa- 

 tion of indifferent substances, while others, over impressed with 

 the thought of a general coordinating force in the organism, 

 deny significance to the orderly play of its cellular parts. 



While opponents of the mdividuahty hypothesis differ thus 

 widely in what they would substitute for it, they almost invari- 

 ably seize upon one supposed condition of the chromosome as 

 a basis for discounting the remaining positive evidence which is 

 presented for the h^-pothesis. Even some well informed cytolo- 

 gists who accept the implications of the facts, regard this cir- 

 cumstance as a severe weakness in the chain of evidence . That 

 the chrom.osomes do not maintain a compact and easily recog- 

 nizable form in the interval between mitoses is accepted by 

 many such biologists as proof that they no longer exist as en- 

 tities. All the other manifold indications of character and con- 

 tinuity do not weigh against this apparent loss of identity. 

 Doubtless it would be more satisfying if we could at all times 

 perceive the chiomosomes in unchanging form in all stages of 

 cellular activity, but why we should demand this condition as a 

 test for individuality in the chromosomes when we unhesitat- 

 ingly admit the unity of an organism in all the varied changes of 

 its development from a single cell, through such complexities of 

 change and metamorphosis as to give rise to doubts of even the 

 phyletic position of some stages, it is difficult to see. Being 

 organic, the chromosomes must change their form, they must 



