m consists essentially of a cabinet large enough to
give comfortable lodgment to a human subject--a cabinet with walls of
peculiar structure, partly of glass, and connected by various pipes with
sundry mysterious-seeming retorts. This single apparatus, however, is
susceptible of being employed for the investigation of an almost endless
variety of questions pertaining to the functionings of the human body
considered as a working mechanism.

Thus, for example, a human subject to be experimented upon may remain
for an indefinite period within this cabinet, occupied in various ways,
taking physical exercise, reading, engaged in creative mental labor,
or sleeping. Meantime, air is supplied for respiration in measured
quantities, and of a precisely determined composition, as regards
chemical impurities, moisture, and temperature. The air after passing
through the chamber being again analyzed, the exact constituents added
to it as waste products of the human machine in action under varying
conditions are determined. It will readily be seen that by indefinitely
varying the conditions of such experiments a great variety of data
may be secured as to the exact physiological accompaniments of various
bodily and mental activities. Such data are of manifest importance to
the physiologist and pathologist on the one hand, while at the same
time having a direct bearing on such eminently practical topics as the
construction of shops, auditoriums, and dwellings in reference to light,
heat, and ventilation. It remains only for practical architecture to
take advantage of the unequivocal data thus placed at its disposal--an
opportunity of which practical architecture, in Germany as elsewhere on
the Continent, has hitherto been very slow to avail itself.

THE MUSEUM OF HYGIENE

The practical lessons thus given in the laboratory are supplemented in
an even more tangible manner, because in a way more accessible to
the public, in another department of the institution which occupies a
contiguous building, and is known as the Museum of Hygiene. This, unlike
the other departments of the institute, is open to the general public
on certain days of each week, and it offers a variety of exhibits of
distinctly novel character and of high educational value. The general
character of the exhibits may be inferred from the name, but perhaps the
scope is even wider than might be expected. In a word, it may be said
that scarcely anything having to do with