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475
on the. periphery: In fig. 1 d is shown the anaphase condition,
the partners of the gemini reaching the poles and the univalents
dividing. Apparently there is, subsequent lo the start of the gemini
parlners toward the poles, no congregation of the single chromo-
somes in the equatorial region preparatory to their division. On
the other hand, they seem to retain throughout the same relative
position which they occupy when first they appear on the spindle.
It would appear from fig. 1 d that rather widely varying num-
bers of chromosomes would be represented in the daughter nuclei.
Thus one might suppose that some of the undivided univalents
near the equatorial region would divide too late to permit their
daughter elements to reach the poles before the rounding up of
the daughter nuclei or that both halves of univalent chromosomes
dividing near one pole would be included in one daughter nucleus.
Although, with the material at hand, the fate of the single chro-
mosomes or their products is not entirely clear, it seems probable
that the latter situation oceurs. On the other hand, it is certainly
true that no conspicuous number of chromosomes is left behind
in the plasma and indeed at interkinesis many P. M. C. show no
such chromosomes and others only one or two. The number of
chromosomes appearing in a homotypic metaphase is rarely less
than nineleen or twenty.
Fig. 2 a shows a characteristic condition following interkinesis,
the significance of which is not entirely clear. It should be noted
that, although widely distributed, the chromosomes all lie in ap-
proximately the same plane within the group and are rather
strikingly large. It is provisionally assumed that such stages, and
they are very numerous, result from abnormal growth of daughter
nuclei during interkinesis, the area occupied by the widely distri-
buted chromosome groups (fig. 2 a) being the same as that occupied
by abnormally large daughter nuclei often to be observed. Since
diads are formed among the tetrads and since intermediate stages
have been observed, it is suggested that such P. M. C. undergo
no further divisions and represent early stages of diad formation.
In contrast to the “abnormal“ condition described above, *normal*
interkinesis stages give rise to typical homotypie metaphases and
to the anaphase condition shown in fig. 2 b. The condilion
illustrated is characteristic of the more *normal* spindles observed.
In many cases the homotypic spindles are highly irregular and in
some cases the two unite to produce a monstrous but regularly
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