On Biastrepsis in its Relation to Cultivation. 
BY 
HUGO de VRIES, 
Professor of Botany in the University of Amsterdam. 
I N his very suggestive volume £ Materials for the Study of 
Variation, treated with especial regard to Discontinuity ’ 
(1894), Mr. W. Bateson says (p. 574), with regard to* the 
relation of the study of variations to the great questions of 
the origin of species and the operation of natural selection, 
‘ The only way in which we may hope to get at the truth is by 
the organization of systematic experiments in breeding, a class 
of research that calls perhaps for more patience and more 
resource than any other form of biological inquiry. Sooner 
or later such investigation will be undertaken, and then we 
shall begin to know.’ 
It is hardly necessary to point out that such experiments in 
breeding can be much more easily carried out with plants 
than with animals, especially when it is necessary to have 
a large number of individuals under observation. This is the 
case at present, since selection is the chief point at issue, so 
that the validity of the conclusions to be drawn depends 
mainly on the number of the individuals in each experiment. 
In the case of plants it is a simple matter to raise several 
hundred individuals, and to retain but a few as the parents of 
the succeeding generation ; it is a much more complicated and 
[Annals of Botany, Vol. XIII. No. LI. September, 1899.] 
