NATURAL SELECTION AND PLANT EVOLUTION 179 
Wealden formations, Professor A. C. Seward, F.R.S., is chiefly 
responsible—has been confined to systematic work, or to iso- 
lated investigations a the structure of solitary—and, as 
plants. 
The inevitable concentration of knowledge and progress around 
. two distinct poles, as it were—the Carboniferous (in England) and 
Jurassic formations (in Aion) , wedged i ween voids 0 
those o t Selection. The very fact of this concentration 
around two definite but separate points has doubtless had, in 
some ways, ul effect upon the study of the other forma- 
which has promised him a more lucrative or profitable field, he has 
hitherto — as barren of interest or objects for research. 
ut it is a good thing that there are still men in this age 
of rush and scramble who will have the qualifying determination 
to probe patiently but decent ges a7 unknown, and to 
iene results during years of careful and dogged sip oe It 
to be hoped that this anh f seevestind: will com be a. 
re rule, as it is now the exception, though the prereiretion of 
a few. 
For the very reason, then, — work aa rip so concentrated 
around two special epochs of past tim has been—and I 
venture to say will yet beiscliegely aaietioel for a long time to 
come. 
nsequently, indications of the existence of such a factor as 
Natural Selection have been confined to a few well-known 
genera, where the structure has been a ‘siveubightedl 
and the evolution of certain structures, e.g. the pollen-tube and 
embryo, has become pretty well known. But in these cases 
Dy L 
the dicotylous Bante but also recent plants, especially 
amongst Gymnosperms and Angio x 
upon Welwrtschia b by De Pearson in South Africa and by Miss 
Berridge upon Ephedra are only two inieheee among many. 
