194 DISTRIBUTION OF THE CHROMOSOMES 
cell, or it may even be torn apart, as if by spindle 
fibers from opposite poles. Consequently less than 
half of the gametes (at least the sperm, for gameto- 
genesis was not studied in the female organs) receive 
theextra chromosome. The proportion varies greatly 
in different individuals. This conforms with the 
genetic result that lata individuals, crossed to la- 
marckiana, give varying proportions of lata offspring 
but never produce offspring more than half of which 
are lata. 
In Primula, a striking case of correspondence be- 
tween abnormal genetic and chromosome phenomena 
has been found, that appears strongly in favor of the 
chromosome hypothesis, although the discoverer, 
Gregory, has hesitated to draw this conclusion. Two 
giant races of the primula (P. sinensis) were found to 
have twice the number of chromosomes character- 
istic of other domesticated races. The breeding ex- 
periments with these plants show that they also have 
a double set of factors as compared with the same 
factorsin ordinary primulas. Whilein ordinary plants 
the chromosomes are paired and, therefore, each 
factor is represented twice, for instance by A and A, 
in the giants there are four like-chromosomes, hence 
four factors AAAA. If the giant race contains some 
factors already mutated, such as A’, the giant might 
contain one, two, three, or four of the mutant 
factors At. Such plants would be AAAA! or AAA'A} 
or AA'A!A! or A'A'A'A'. As stated above, the 
breeding work shows that there is a double set of 
factors, but the evidence is as yet insufficient to de- 
