322 LESTER W. SHARP 



The individiiality of the chromosomes. 



This question can only be touched upon at this time. Having in mind 

 the events as we hâve described them for Vida — the telophase association 

 of reticulate bands each representing a chromosome, the visibility of such 

 bands during rest, and their prophasic isolation and condensation to chro- 

 mosomes — it is ver}' natural to draw the conclusion that the chromosomes 

 are preserving their autonom}' through the resting stages. This is especially 

 impressed upon the observer as he sees the aspects of the telophase du- 

 plicated in the prophase, the processes being repeated in the reverse order. 

 He can hardly regard such a succession of events as other than very strong 

 visible évidence for the individuality of the chromosomes. 



This simple statement of the case is very far from being a fuU one. 

 Not ail forms show such striking évidence as does Vicia. This is to be 

 expected, since no process believed to be fundamental or of gênerai 

 occurrence is equally well exhibited by ail organisms. In many cases the 

 telophasic transformation is more complète. We cannot rely upon direct 

 observation to show that in such forms, or even in Vicia itself the reticulum 

 breaks down precisely along ail the lines where the chromosomic bands 

 joined at telophase. The same should be said ot the forms in which the 

 chromosomes are reported to fragment more or less irregularly at telophase. 

 But in ail cases the resting structures give rise to a certain number of 

 chromosomes with almost perfect regularity. 



The above considérations suggest the existence of a more fundamental 

 cause for the autonomy and fréquent structural iiidependence of the chro- 

 mosomes during rest and their reappearance at prophase — a cause of 

 whose nature we are as yet unaware, but whose effects are visible in the 

 phenomena exhibited in cases like Vicia. Althongh the theory of the auto- 

 nomy of the chromosomes is thus held to be supported by a strong basis 

 of observed facts, we believe the underlying principles governing this 

 autonomy are yet to be sought. 



