BETTER ADAPTATION OF PLANTS 349 
that must be put into it. But if desirable and well-adapted species 
are not available for the regions concerned, a condition which 1s 
more or less true for most of the regions of the earth having a Mediter- 
ranean-type climate, with long, rainless summers, then this radical 
method of breeding may in time be rewarding.” (Italics mine.) 
As will be pointed out later, I cannot agree with the italicized 
portion of the above statement. 
There is general agreement with Stebbins’ statement that at 
least 70% of grass species are allopolyploids, the result of wide 
crosses. But there is also general agreement that newly developed 
(the so-called raw) amphidiploids are quite dissimilar to old es- 
tablished allopolyploids, especially in their cytogenetic behavior 
(7). This does not mean that, ultimately, benefits will not be 
reaped from interspecific hybridization. It does mean that results 
from such a program are likely to be very much in the future. 
Love (36, 38a) called attention to the difficulties inherent in 
such radical hybridization programs. In 19§2 he outlined the fun- 
damental research needed to put such a project on a sound, sci- 
entific basis after reviewing this field of endeavor. The review 
showed beyond a doubt that the best chances of success would be 
obtained from beginning hybridization work at the diploid level. 
He also called the attention of the world’s grass breeders to an 
entirely new development (17, 58). 
They found that ‘colchicine treatment of full sibs of a true- 
breeding variety of sorghum gave variants possessing a number 
of ancestral characteristics of which some bred true immediately.” 
This treatment of emerging shoots does not necessarily cause 
polyploidy, but may also cause somatic reduction. Huskins (26), 
who pioneered this work, wrote: “If the production of homozygous 
diploid tissues could be induced frequently enough, it would have 
some advantages and few disadvantages for the plant breeder 
over the production of haploids.” 
Clausen (4) and his colleagues have pioneered a new field by 
hybridizing apomictic species of Poa that belong to distinct sec- 
tions of the genus. They have crossed forms so widely separated 
geographically that they previously had no opportunity for hy- 
bridization. They have obtained transgressive segregation and 
