THE YOUNG PROFESSOR 173 
let you have of our European animals what will be in my power 
to procure and I hope you will mention your desiderata as freely as 
I mention mine. I should greatly value all your bats, mice, rats, 
moles, shrews, weasels, squirrels, etc. 
Though I am not much of a botanist, there is nevertheless one 
branch of that science in which I take the deepest interest and for 
which I would also ask your assistance. The study of trees has become 
so important to paleontologists, that no one who has paid some 
attention to fossils can any longer make progress in this department 
without studying the fossil trees and comparing them with the actual 
flora. Now, I know you have paid much attention to this subject, 
and to me it had acquired a new degree of interest since I have 
ascertained that the arborescent flora of the European Miocene 
Tertiary deposits has the greatest affinity with the actual flora of 
the temperate regions of the United States; a result entirely unex- 
pected, and quite contrary to most of the prevailing notions about 
the temperature of the continent of Europe during the tertiary 
epoch. I am now very desirous to make extensive collections of 
all the trees and shrubs of the United States in order to trace as far as 
possible this analogy. But such a collection cannot be found in any 
herbarium, it must be made anew with that peculiar view; and if 
you feel the least inclined to help me in this enquiry, you would 
not only help me, but really help advancing one of the most interesting 
geological questions. If you find it too troublesome, forgive me for 
having asked for it. As fossil plants are mostly found in parts, it 
would be necessary to have 1°, young branches with the buds as 
they are now before opening; cut such specimens as can be dried 
between paper; 2°, branches with young bark, one or two inches in 
diameter; cut cylinders of about six inches length; 3°, similar cylinders 
of the stems, old wood with old bark; then mark the tree to collect 
at a later period, flowers, fruits, and leaves, and of the last, a great 
number of all varieties of form from different branches and recent 
shoots. It is almost late to begin, but I could not write earlier, and 
in fact, it is rather imprudent for me to go to-day through the exer- 
tion of writing; but perhaps in the thickest of the woods, you will 
still find specimens of all your species in a leafless state, with the 
buds in the winter state. 
