the trap will be washed clean by the water at each discharge, and in
which the lever movement of the handle will not allow of the passage
of sewer gas.

And now just a few personal remarks in conclusion. I have had much
pleasure in giving to my old brother officers in these lectures the
result of my experience in sanitary science. In doing so, I desired
especially to impress on you who are just entering your profession the
importance of giving effect to those principles of sanitary science
which were left very much in abeyance until after the Crimean war. I
have not desired to fetter you with dogmatic rules, but I have sought,
by general illustrations, to show you the principles on which sanitary
science rests. That science is embodied in the words, pure earth, pure
air, pure water. In nature that purity is insured by increasing
movement. Neither ought we to stagnate. In the application of these
principles your goal of to-day should be your starting-post for
to-morrow. If I have fulfilled my object, I shall have interested you
sufficiently to induce some of you at least to seize and carry forward
to a more advanced position the torch of sanitary science.

* * * * *

PASTEUR'S NEW METHOD OF ATTENUATION.

The view that vaccinia is attenuated variola is well known, and has
been extensively adopted by English physicians. If the opinion means
anything, it signifies that the two diseases are in essence one and
the same, differing only in degree. M. Pasteur has recently found that
by passing the bacillus of "rouget" of pigs through rabbits, he can
effect a considerable attenuation of the "rouget" virus. He has shown
that rabbits inoculated with the bacillus of rouget become very ill
and die, but if the inoculations be carried through a series of
rabbits, a notable modification results in the bacillus. As regards
the rabbits themselves, no favorable change occurs--they are all made
very ill, or die. But if inoculation be made on pigs from those
rabbits, at the end of the series it is found that the pigs have the
disease in a mild form, and, moreover, that they enjoy immunity from
further attacks of "rouget." This simply means that the rabbits have
effected, or the bacillus has undergone while in them, an attenuation
of virulence. So the pigs may be "vaccinated" with the modified virus,
have the disease in a mild form, and thereafter be protected from the
disease. The analogy between th