310 CGNOTHERA AND THE MUTATION THEORY 
by deVries, Stomps, and Bartlett that undoubted 
wild species of Ginothera show the same kind of 
behavior as Lamarckiana, and like it produce 
numerous new types. 
The next suggestion as to the cause of the un- 
usual behavior of Cinothera came with the dis- 
covery by Lutz that the ‘‘mutant”’ gigas has twice 
as many chromosomes as has the parent form, 
Lamarckiana (the diploid numbers being 28 and 
14, respectively). The situation is complicated by 
the fact that there are apparently races that look 
like gigas but have only 14 chromosomes. These 
two races thus closely parallel the two giant races 
of Primula sinensis of which one is diploid and the 
other tetraploid. ‘The aberrant numbers observed 
in gigas hybrids by Stomps may perhaps be due to 
a process of fragmentation of chromosomes similar 
to that described for O. scintillans by Hance. 
Another type of variation in chromosome number 
has been described by Gates and by Lutz. The 
“mutant” types lata, semilata and scintillans have 
15 chromosomes as: the diploid number, instead of 
the 14 characteristic of Lamarckiana. As would 
have been expected if the extra chromosome is re- 
sponsible for their peculiarities, these forms do not 
breed true. Each regularly produces many typical 
Lamarckiana offspring, as well as other offspring 
like itself. These cases have already been discussed 
under non-disjunction (see Chapter VI). 
Although differences in chromosome number due 
to irregularities in reduction or fertilization may be 
