1904] BRIEFER ARTICLES 467 
mentation, and as to the method of their separation, are in harmony 
with the more recent results of Strasburger (’0o) and Mottier (’03). When 
the equatorial plate is formed, the majority of the chromosomes are 
attached at or near one end to the spindle; but a few are attached at 
the middle or at some point between the middle and one end. In the 
commoner case, that of the attachment at one end, the daughter chro- 
mosomes separate from each other as straight rods; but just before the 
completion of the separation, each daughter chromosome splits longi- 
tudinally, the halves diverging at their equatorial ends and remaining 
in contact by the ends directed toward the pole, giving a V-shape to 
the daughter chromosome. It is often evident that this second longi- 
tudinal split extends the full length of the daughter chromosome, the 
granddaughter chromosomes so produced remaining in contact, how- 
ever, at their polar ends. 
In the separation of the halves of a chromosome whose attachment 
is at or near the middle, each daughter chromosome becomes bent at 
the point of attachment and assumes, during the separation, a U or 
V-shape. When, therefore, the second longitudinal split occurs, such a 
daughter chromosome is divided into two V’s, which remain in contact 
at their angles. This variation in the appearance of the daughter 
chromosomes, due to the method of their attachment to the spindle, 
has been responsible for much of the confusion that has existed regard- 
ing the nature of the heterotypic division in plants. | 
After the gathering of the daughter chromosomes at each pole of 
the spindle, they become curved, bent, and crowded together into a 
dense mass, about which a nuclear membrane is formed. ‘lhe curving 
is such that a free end of one granddaughter chromosome (turned 
toward the equatorial plane of the spindle) comes into contact with a 
corresponding end of another chromosome. Whether these ends 
become fused, forming a continuous spirem, I have been unable to 
determine. At any rate, very early in the prophases of the homoeotypic 
division, some time before the disappearance of the nuclear membrane, 
the thread loosens and spreads apart to some extent, and it is then seen 
to be composed of segments, which have the shape of V's with curved 
arms, and which occupy exactly the same position as did the daughter 
chromosomes in the anaphases of the preceding division. There can 
be no doubt, I think, that the V-shaped chromosomes of the homoeotypic 
division are identical with the daughter chromosomes of the heterotypic 
division. 
' These V shaped chromosomes become arranged in the equatorial 
