420 MITCHEL CARROLL 
mals were collected in 1909 and some in 1915, the extra elements 
or the tendencies to form them were probably transmitted through 
that interval of time. Extra chromosomes do not apparently 
accumulate in this material any more than in Trimerotropis. It 
may be that if more than three get into one gamete, some degen- 
erate or are eliminated from the nucleus, or even the gamete 
may be non-viable as in the case of XXX zygotes in Drosophila 
(16). Butit is obvious since the supernumeraries in this material 
are genetically related and when paired synapse and segregate 
during maturation that, irrespective of the non-viability of 
gametes or the elimination of extra elements from the nucleus, a 
regulative process which insures disjunction and prevents piling 
up, to a great extent at least, is present. 
E. The extra chromosome as a factor in heredity 
When the entire chromosome complex is doubled, as in certain 
Oenotheras (Gates, ’09, 711; Davis, ’11), the somatic characters 
of the individual may be profoundly influenced by the doubling. 
In Drosophila we have a well-known instance of the effect of an 
extra chromosome on the soma (Bridges, 713, 714, 716). A 
single odd supernumerary may be one of the important factors in 
producing some Oenothera mutants (Lutz, 712, ’16, 717; Gates 
and Thomas, ’14; Hance, ’18 a, ’18b). 
The extra tetrad in Camnula is the only supernumerary pair, 
behaving at synapsis like a typical euchromosome pair, so far 
reported. Hence it is a matter of some importance to discover if 
there is any correlation between the distribution of this element 
and somatic characters. While the specimens from which came 
the material used in the present study are all preserved in this 
laboratory, it would be futile to attempt to work out the above 
correlation until a large number of individuals have been ana- 
lyzed cytologically. This problem can be more satisfactorily 
attacked, too, with predigreed animals, and so may be laid over 
until it is possible to undertake some breeding work. 
It seems likely that, in the germ tract of individuals in which 
it occurs, the camnulan extra chromosome may regularly suffer a 
