DISTRIBUTION OF THE CHROMOSOMES 193° 
ever, no data concerning the genetic behavior of the 
hybrids have been reported. 
Another instance of parallelism between unusual 
chromosome phenomena and genetic results is that 
found in (Enothera lata and semilata by Lutz, Gates 
and Thomas. The normal chromosome number in 
(nothera lamarckiana is 14, but the race called lata 
always has 15 chromosomes, 7.e., one kind of chromo- 
some exists in the triploid number. This is true 
even of lata plants which originated independently 
of the ordinary stock, in widely different races of 
(Enothera. The same results apply to semilata, 
which appears to be a variety of lata. Lata and semi- 
lata occasionally arise ‘spontaneously ” from lamarck- 
iana, in a small per cent. of the offspring of any one 
individual, and the explanation for this may be found 
in the fact that occasionally, in the gametogenesis 
of lamarckiana, two mated chromosomes, instead of 
separating, pass to the same pole (non-disjunction) 
so that the offspring would have three chromosomes of 
this type and contain 15 chromosomes in all. The 
behavior of the extra chromosome in the lata indi- 
viduals is also of interest, for it is found that in 
gametogenesis, when the mated chromosomes sepa- 
rate, the extra chromosome does not divide regularly 
as do unpaired chromosomes in moths, but tends to 
pass to one pole. This would result in half the 
gametes containing it and transmitting the lata con- 
dition and the other half being normal. Very often, 
however, the chromosome lags on the spindle and 
so fails to be included in the nucleus of either daughter 
