The origin of adaptive variations gave him, at that time,

little concern
The origin of adaptive variations gave him, at that time,
little concern. Though keenly appreciative of the problem of
variation which his studies in evolution presented, he
dismissed it in the 'Origin' with less than twenty-five pages
of discussion. Such brevity is not surprising, since a more
extended treatment would only have embarrassed the progress of
the argument. In fact, his restraint in this direction enabled
him, first, to avoid the difficulties into which Lamarck, with
his bold attack on the problem of variation, had fallen; and
second, by doing so, to deal the doctrine of Design a blow from
which it has never recovered.