FUNDAMENTALS OF PLANT BREEDING 185 
methods of genetical research are of immediate service to the 
practical plant-breeder, and in advancing claims for those methods 
which experience can asnaky ogee ify. 
A consequence, the men engaged in the work of plant 
e 
method of the practical breeder has transformed Nature. 
The teacher of genetics undertakes to show that man how the 
work may be done with hep hese and completeness. Yet 
cu a. 
ractical man produced these pure breeding races long ago; the 
geneticist is not able at the present moment to lay down precise 
re obedience to which would lead to the result already 
ieve 
Des is that, although the general reader will find Pro 
Goulbar’s Ss ae interesting, the practical man must still await a 
we hae = he needs. 
The second defect which this book shares with pte of its 
kind is the seeds to state precisely what it claims to As 
an example, we may choose the chapter on How va tacks 
Drought-resistance. The writer points out that 2g a 
quality. He avers that the ihoaahicaisbanhe: a ae be 
brought up to the standand of quality by continuous goaaidegibe 
admitting that it may be a slow process; but, for our part, w 
know of no recorded case in which selection 4 done this wo ae 
d 
mbination in a hybrid As to the method to be followed, all 
that is vouchsated is the following statement which, by its 
reticence, is frankly useless :—‘ It will be remembered that the 
desired combination will not occur in all the progeny; but if 
h ; 
quality be 
charactors only — i the progeny of the hybrids ae soslitiee 
the desired combin 
Hven though we assume that drought-resistance (D) and 
quality (Q) are unit characters, the statement is —_ Pel y in 
that case we have by crossing Dq an a -—-F, = q, 
all have in sixteen offspring nine with the 
the 
we 
jaa combination but of nine only one is pure for these 
If, reover, as 
‘“‘ character ” is a PR a or if it depend not on a single factor 
but on several—and quality may well depend on many—the 
problem becomes far more complicated than would appear 
Journat or Borany.—Vot. 53. [Junn, 1915.) P 
