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We have now to consider the bearing of the observations described 

 in this paper on the hypothesis of "chromosome-individuality". If my 

 -observations are correct, mitosis can no longer be regarded as the 

 sole or even as the chief method of division in all forms under normal 

 conditions. This holds good for the germ cells as well as for the 

 somatic cells. In the light of these facts it at once becomes im- 

 probable that the chromosome possesses the fundamental significance 

 attributed to it. It may be asserted by supporters of the chromosome 

 hypothesis that there is an invisible grouping and division of the 

 specific substances in amitosis as well as in mitosis, but such an as- 

 sertion cannot at present be proved or disproved by observation since 

 the postulated phenomena are invisible. In other words, it involves 

 the formulation of a new hypothesis unsupported by facts, to save 

 the old one from destruction. The chromosome hypothesis is the pro- 

 duct of inference from direct observation, and if we proceed on the 

 basis of direct observation of amitosis alone, we are as fully justified 

 in believing that the chromosomes possess no fundamental significance 

 in nuclear division as are the supporters of the chromosome hypo- 

 thesis in the opposite belief. But the question of significance aside, 

 it is probable, as I have attempted to show, that the processes involv- 

 ed in the two forms of division are diö'erent in character, and that 

 the differences in visible phenomena are the result of that difference. 

 It is improbable, to say the least, that a constant or characteristic 

 grouping or an equal division of specific substances occurs in amitosis. 

 No visible change occurs in the chromatin, which is often scattered 

 throughout the nucleus during the whole period. 



Moreover, the division is often unequal, but there are no grounds 

 for believing that there is any physiological difference between daughter 

 nuclei. In the developing ovary of Moniezia, for example, such unequal 

 divisions are very frequent, yet I have never seen indications of nuclear 

 degeneration and all the cells produce ova. If amitosis were found 

 only in somatic cells while the germ cells always divided mitotically 

 there would be more reason for believing that the chromosomes might 

 possess some special significance in connection with the "transmission 

 of characters", but, as I have shown, amitosis may be the characte- 

 ristic method of division at certain stages in the germ cells of certain 

 species. If the chromosomes are not of fundamental importance here 

 why should they be elsewhere? After the conclusion of a longer or 

 shorter series of amitotic divisions in these cases the condition known 

 as synapsis appears, a condition regarded by the supporters of the 

 chromosome hypothesis as of great importance, but which seems to 



