752 
INTRODUCTORY ADDRESS. 
knowledge has been developed by slow degrees, and may be 
justly said to be a child of the present age just beaming forth 
into manhood. It has mainly depended for its advancement 
upon the discovery and improvement of the microscope. The 
study of histology is a natural consequence of the ardent 
pursuit and progress of anatomical knowledge ; for when all 
the larger parts of the organization have been examined and 
described, when the relative position of the muscles and the 
ramifications of vessels and nerves have been accurately deter¬ 
mined, the next thing is to inquire, by the eye and the mi¬ 
croscope, what is the constitution of them—what the minute 
and intimate parts of their structure are, and, in short, of 
what ultimate visible atoms they are composed. Roundly 
speaking, we may say that the frames of all organic beings 
consist primarily of so many infinitesimal cells, or organic 
beads, ranged and strung by the vital principle into all the 
varied forms that constitute the bodies of animals, and of man, 
of course. Between the primordial cell and the tissue that is 
made of such cells there are numerous stages of transforma¬ 
tion, aggregation, and composition, affording a vast field of 
intermediate research, on the border of which you may stand, 
as on the shore of a sea, and learn some little about it without 
departing from the terra firma of more practical, science. It 
is useful for you to study this branch of science, in order that 
your thoughts may not be too limited in a calling that 
depends for much of its success upon intuition and the free 
play of the mental faculties. In short, though many things 
may look useless to us in practice; this is their justification, 
that they encourage, enfranchise, and embolden the mind, 
exercise it gymnastically, and so fit it to overcome difficulties, 
and fill it with skilful resources. This justification applies 
very pertinently to a microscopic examination of the fluid 
constituents of the body, of which, without a minute investi¬ 
gation by vision assisted by art, almost nothing could be 
known. For instance, take the blood. Common observation 
reveals nothing more than that the blood is a variably red 
fluid, which, when drawn from the body, gradually coagulates, 
dividing into a clot and a limpid fluid called serum, and that 
the clot on its upper surface has a yellow appearance, while 
its lower part assumes a red hue. There is not much to 
reason upon^ here. These observed facts are coarse and 
scanty; and as I may say, they merely open to us the gate of 
further inquiry. The microscope, however, comes and ex¬ 
hibits to us a wondrous fluid mechanism, all the parts of 
which are connected together by vital attractions, and have 
their necessary functions. It shows to the eye the preva- 
