The Making of Species 
tion is practically zz/, We do not even know 
along what particular lines mutations occur. 
We have yet to discover whether one mutation 
invariably leads to another along the same lines 
—in other words, whether mutating organisms 
behave as though they had behind them a force 
acting in a definite direction. The solution of 
these problems seems afar off. The hope of 
solving them lies, not in the speculations in 
which biologists of to-day are so fond of in- 
dulging, but in observation and experiment, 
especially the last. 
The future of biology is largely in the hands 
of the practical breeder. 
388 
