leave Brucke
and Kolliker to settle if they can.

No one has shown satisfactorily the process by which the
blood-corpuscles are formed out of the lymph-corpuscles, nor what
becomes of them. These two questions are like those famous household
puzzles,--Where do the flies come from? and, Where do the pins go to?

There is a series of organs in the body which has long puzzled
physiologists,--organs of glandular aspect, but having no ducts,--the
spleen, the thyroid and thymus bodies, and the suprarenal capsules. We
call them vascular glands, and we believe that they elaborate colored
and uncolored blood-cells; but just what changes they effect, and
just how they effect them, it has proved a very difficult matter to
determine. So of the noted glandules which form Peyer's patches, their
precise office, though seemingly like those of the lymphatic glands,
cannot be positively assigned, so far as I know, at the present time.
It is of obvious interest to learn it with reference to the pathology of
typhoid fever. It will be remarked that the coincidence of their changes
in this disease with enlargement of the spleen suggests the idea of a
similarity of function in these two organs.

The theories of the production of animal heat, from the times of Black,
Lavoisier, and Crawford to those of Liebig, are familiar to all who have
paid any attention to physiological studies. The simplicity of Liebig's
views, and the popular form in which they have been presented, have
given them wide currency, and incorporated them in the common belief and
language of our text-books. Direct oxidation or combustion of the carbon
and hydrogen contained in the food, or in the tissues themselves; the
division of alimentary substances into respiratory, or non-azotized,
and azotized,--these doctrines are familiar even to the classes in our
high-schools. But this simple statement is boldly questioned. Nothing
proves that oxygen combines (in the system) with hydrogen and carbon
in particular, rather than with sulphur and azote. Such is the
well-grounded statement of Robin and Verdeil. "It is very probable that
animal heat is entirely produced by the chemical actions which take
place in the organism, but the phenomenon is too complex to admit of our
calculating it according to the quality of oxygen consumed." These last
are the words of Regnault, as cited by Mr. Lewes, whose intelligent
discussion of this and many of the most interesting physiological
probl