322 Cincinnati Society of Natural History. 
cup, to one which has a fringe half an inch long. The cups are shal- 
low and deep, thick and thin, extending half way up the acorn, reach- 
ing to its apex, or almost entirely concealing it.* 
It seems to me that in this marked tendency to variability in the 
Quercus macrocarpa, we have the beginnings of what might, in the 
course of time, come to be considered several distinct species. If the 
tree springing from the acorn distinguished by the thin-walled cup, 
destitute of fringe, should produce a preponderance of acorns of the 
same character, and if this character should be transmitted from 
generation to generation, as we have every reason to suppose may be 
the case, then in the course of time a new variety or species will have 
arisen. If, further, the acorn with the long fringe produces in its turn 
a tree bearing acorns like the original one, and its characters be also 
transmitted and finally fixed, another and a widely different variety 
or species from. the thin-walled variety will have arisen. If now we 
imagine through any cause all the intermediate forms to become ex- 
tinct, and only the extremes remain, it would be hard to realize 
that two such different looking forms could have arisen from one 
which produced both kinds of acorns. 
Such facts as have been given in this article, and cases of the same 
kind, are by no means rare, should make naturalists careful how they 
make new species. It is much more creditable in the present state of 
our knowledge to reduce the number of species, than to increase it. 
For it is very much easier to arbitrarily establish the bounds of a 
species, and to say this is one, and that another, than to say this 
species and that species are forms which in the past were closely 
connected; and to say that they ought now to rank as varieties, either 
one of the other, or else of some other species possessing characters 
common to both. 
* The oak said to most closely resemble our Q. macrocarpa,which, by the way,is principally 
confined to the Mississippi valley, is the QY. cerris of Europe. This is as variable as the Q. 
jacrocarpa. 1tisa native of middle and south Europe, and of western Asia, and Loudon in 
his Arboretum et Fruticetum Britannicum, remarks on the tendency to sport which is char- 
acteristic of it. He ‘gives no less than fourteen varieties of it, and these vary from forms 
with pinnatifid or sinuate leaves, to dentate, to subevergreen, and even evergreen leaves. He 
says nothing about any variation in the fruit. 
