516 WHITE: THE SALTATORY 
character to those described by Professor de Vries, and the brief 
discussion I shall give them will be in accordance with that con- 
viction. But to illustrate my remarks upon them it is necessary 
to briefly state the nature of his mutation theory and the methods 
he has pursued in demonstrating it; and also to show wherein it 
differs from the generally accepted Darwinian theory. For the sake 
of brevity these statements are mostly made in epigrammatic form. 
It is my purpose also, as far as possible, to present this brief 
sketch of the theory and its demonstration from the author’s 
point of view, albeit in words of my personal choosing.* 
The Darwinian theory of the origin of species by natural 
selection teaches that species have been produced from one 
another, through lines of genetic descent, by a process of evolu- 
tional variation which is immeasurably slow, even in its most 
accelerated cases; that one of the chief causes of specific change 
is the competitive struggle for existence to which all organisms 
are subjected; and that variation is incipient species-building. 
The enunciation of this theory was a strong and effective plea in 
favor of the origin of species by the operation of natural law as 
opposed to the then-prevailing belief that every organic form has 
arisen by a special act of creation. It has served a grand purpose, 
especially in establishing the doctrine of evolution on a firm basis, 
and if its candid and eminent author were now living he would be 
among the first to welcome any change in it that might prove to 
be necessary in view of later discovered facts. . 
The de Vriesian theory of mutation is in entire accore | 
natural law and also with the doctrine of the evolutional origin © 
species through lines of genetic descent, but it especially make? 
clear distinction between species and varieties and teaches the sud- 
den origination of the former whether they possess more or less 
strongly marked attributes. It also teaches a far more stable e"- 
tity of species than one can conceive of who unqualifiedly accept 
the Darwinian theory. Professor de Vries logically assumes th# 
the mutation theory is as applicable to animals as to plants, but he 
has formulated it only with reference to the latter. I shall make 
given by me ip 
ing gem 
1902. 
d with 
* A somewhat fuller, but brief, statement of the mutation theory is 
the Annual Report of the Smithsonian Institution for 1901. An interest 
sketch of the theory by Professor de Vries is contained in Science for May 9 
