1908] GATES—REDUCTION IN OENOTHERA 17 
tudinal split appears in the daughter chromosomes. ‘This split does 
not stop short of one end, giving a V-shaped body as in many plant 
chromosomes, but usually passes right through, forming two inde- 
pendent bodies, which, however, remain paired in the telophase and 
occupy a great variety of positions in regard to each other. The 
homotypic chromosomes thus assume many of the characteristic 
shapes which are usually observed in the heterotypic chromosomes of 
other forms, such as X, Y, V, H, etc. The failure of the heterotypic 
bivalents to form these shapes is due partly to the weaker attraction 
between the members of a pair, but largely to a difference in their 
shape, each member of a pair being usually more rounded in the 
heterotypic and more elongated and rodlike during the stages between 
the two mitoses. 
The telophase of the heterotypic mitosis is one of the best stages for 
counting the chromosomes, as they are distributed at equal intervals 
around the periphery of the nucleus, no two ever being in contact and 
the halves of each (bivalent) chromosome rarely separating. The 
chromosomes now evidently repel each other, while the halves of 
each chromosome attract each other rather strongly. The halves of 
these bivalent chromosomes are usually short rods, but they may be 
dumb-bell ot hour-glass shaped, or nearly globular, as previously 
mentioned (12). Sometimes, however, this split fails completely to 
occur in the anaphase, the daughter chromosomes remaining single 
and globular or somewhat elongated (fig. 39). These telophase 
stages and the prophases of the homotypic mitosis will be taken up 
in detail in a paper dealing with different forms. These results, 
therefore, will not be duplicated here, but a brief statement of the 
events of the second mitosis will be given. | 
HOMOTYPIC MITOSIS 
: In the telophase of the heterotypic mitosis the nuclei never pass 
into the resting condition and the chromosomes never lose their 
identity completely, though they spread out and anastomose with 
each other more or less. Nucleoli are formed, as previously described 
(II). These stages between the two mitoses last for some time, but 
the events of the second mitosis are passed through very quickly. The 
‘wo homotypic spindles are formed simultaneously and their axes are 
