70 
of “connecting links” between old species and new ones, and 
was obliged to invoke “the imperfection of the geological 
record” and other causes to account for it; but the mutation 
theory offers an easier explanation of these /acunae. As i 
says: ‘‘ The intermediates are lacking simply because they have 
never existed.” Darwin likewise found difficulty in the want of 
intermediate forms of fossils in consecutive geological strata, but 
this obstacle is overcome by the theory of de Vries, for of course 
mutations have probably occurred in past ages as they are now 
nown to occur in the present. Another subject of perplexity 
to Darwin was the immense length of time required by his theory 
for the development of the present living world from its prime- 
val ancestors, and it is well known that the geologists and the 
physicists declined to allow him the enormous periods demanded 
But the mutation theory very greatly reduces these demands and 
so brings the general theory of derivation into harmony with 
opinions which were formerly supposed to be in a measure an- 
tagonistic to it. These are only a few examples of the help de 
Vries has brought to the doctrine of evolution. 
he publication in English of his views and discoveries is a 
notable event, and is a matter of special Beeclca to members 
of the New York Botanical Garden, since Doctor MacDougal, 
our assistant director, has been intrusted with the duty of edit- 
ing the work in which they appear, and Miss Vail, our librarian, 
has been able to render him efficient assistance. 
res F. Cox. 
