(ENOTHERA MUT. J.ATA AND (E. MUT. SEMILATA. 547 
LiDusual case the distribution of chromatin has apparently not 
been in strict accord with the law of chi*omosome individu- 
ality. It is one of the rare exceptions which serves to 
emphasise the almost nniversal character of the rule. 
The homotypic anaphase represented in fig. 45 is similar to 
that shown for lata rnbri calyx in fig. 29, except that the 
number of chromosomes in each of the four groups is 7. 
The Lata-like Mutant (No. 229 . I . 10). 
In all the lata forms the chromosomes appear to be rather 
more viscous than in otlier CKuotheras^ and hence there is 
often an exceptional amount of variation in shape. Figs. 46- 
51 are taken from the lata-like mutant in a culture from 
Sweden^ already described (p. 531). Fig. 46 is a heterotypic 
metaphase showing 15 chromosomes. Strictly speaking, in 
CEnothera there is no heterotypic metaphase, for, with rare 
exceptions, the chromosomes are at no time arranged in 
i-egular paired alignment on the heterotypic spindle. But 
nevertheless there must be balanced forces controlling the 
movements of the chromosome pairs at this time, since the 
segregation of the chromosomes results, in nearly all cases, 
in an equal distribution of the 14 bodies. And there is 
every reason to believe, from analogy with other cases, that 
the chromosome pairs which separate on the heterotypic 
spindle are the same as those which are so frequently obviously 
paired in the metaphase of somatic mitoses. 
In fig. 47 the heterotypic cliromosomes are segregating so 
that apparently 9 whole chromosomes will reach one pole of 
the spindle and only 5 the other. The 15th chromosome, 
which is presumably the impaired or extra chromosome, is 
dividing, not by a regular longitudinal fission, but by pulling 
apart in an irregular way, perhaps transversely, leaving a 
trail of chromatin between the tivo halves. Such a condition 
was found a number of times in this plant. Fig. 48, in which 
the spindle appears to have been slightly cut, shows a similar 
behaviour of the extra chromosome. In fig. 49 one chromosome 
