200 General Notes. [ March, 
be invisible from above. Yet, as we have seen, their self-fertilization 
is impossible. These and other facts have led me to the conclu- 
sion that, where fertilized at all, it is chiefly done by ants, which, 
on the theory, now generally accepted by entomologists, of the 
possession by that insect of a keen sense of smell, would suffi- 
ciently account for the exquisite fragrance of the flowers of 
Epigæa. I have failed entirely to find insects within the corolla, 
but this, so far from causing doubts that it is fertilized by insect 
agency, simply helps us to understand why it bears fruit so 
sparingly. 
The facts which I have stated, even if they were entirely new, 
which they probably are not, might not, perhaps, in themselves 
have justified me in E for them the attention of this asso- 
ciation. For my own part I am far more interested in the 
important stints Cilio they illustrate, and it is for the pur- 
pose of stating these principles, supported by such an example, 
that I have been led to present the fact 
Besides affording an instructive senii of the many ways i in 
which plants are depencent upon insects, Epigzea well illustrates 
the process of sexual differentiation which is going on in a great 
many species of plants. In the maples it has not yet advanced 
so far; in Smilax it has gone somewhat farther, while in the wil- 
low it has reached completeness. It isin these intermediate stages _ 
that the phenomena are most interesting, and the botanist, con- 
templating a great number of these, differing by small degrees, can 
almost see the process in operation. The phenomena of dimorph- 
ism, as it exists in Houstonia, must probably be regarded as one 
of the initial steps in the direction of ultimate dicecism, or com- 
plete separation of the sexes. 
In this respect, as in many others, we find that nature cannot 
be assumed to have reached its final and fixed condition, but that 
the existing state of things must be regarded as dynamic; the 
movements in the past which have made things what they 
are, still continue to effect changes in them. There is a sort of 
uniformitarianismn i in biology as well as in geology, and the Jaw of ; 
causes” is as potent in explaining the existing conditio 
of crane and animals as it is that of coast lines or mountains. z 
Hermaphroditism, or self-fecundatien, seems to be a thraldom 
necessary at the outset, but from which all living things are seek- 
ing to escape. The animal kingdom has, for the most ft i 
Bo which I have a a here, shows one of the many wa! 
in which these creatures r pa this service. 
