SOMATIC CHROMOSOMES IN VICIA 3l7 



a médian section of a nucleus at this time. On account of the thinness of 

 the section the chromosomes are eut into small pièces; thèse show the spHt 

 clearly. In cells situated in improperly fixed tissue the split is made out 

 with the greatest difficulty if at ail, as lias been described above for the 

 preceding stages. Thus it is on such grounds that the writer interprets the 

 results of Bonnevie (o8, ii) and of Gates (12) who state that the split 

 visible in the early prophases closes completely during the late prophases, 

 a new one appearing as the définitive split. 



In the chromosomes during the late prophases J'icia shows no such 

 " chromosome axis '- as Bonnevie (08) has described, but which is absent 

 from her igii account. It can only be said that the interior of the chro- 

 mosome is probably less dense than the peripheral portion. 



The nuclear membrane now disappears and the chromosomes loosen 

 up as an irregularly arranged group ('). The halves at this time are 

 very distinct, in many places not touching each other. Since this stage is 

 rare in the material, as Fraser and Snell (ii) hâve also stated, it is pro- 

 bable that it is of very short duration. The chromosomes become arranged 

 on the spindle at once after being freed by the dissolution of the nuclear 

 membrane. 



In support of the gênerai view that the définitive splitting of the 

 chromosomes occurs at prophase in a homogencous band or thread may be 

 cited the following works. The list is by no means complète. Grégoire 

 and VVygaerts (o3) on Trillium, Karpoff (04) on Vicia, Martins Mano 

 (04) on Phasaeoliis and Solaiiiiin, Grégoire (06) on Alliiim, Yamanouchi 

 (08) on Nephrodiiim, Bonnevie (08, 11) on Ascaris, Amphiuma and 

 Allium, Nëmec (10) on Alliiim, Stomps (10) on Spiimcia, Gates (12) on 

 Oenothera, Digby (^2) on Primiila. 



This brings to completion the description, which began with the ar- 

 rangement of the chromosomes upon the spindle. 



(') The figure iilustrating this stage has been inadvertently omitted from the plates. 



