Page 127 - My FlipBook

occur in animals. Abrasions that have become discolored,
absorption about the necks of the teeth and many conditions
of this kind occur in animals the same as in man, but pro-
gressive caries that contains the micro-organisms and con-
tains the enlarged tubules which make up the characteristics
of caries in man, I have never seen in the teeth of any animal.
Diseases that afYect man may affect certain animals.
Man, monkeys, cattle, sheep, guinea pigs, rabbits, etc., have
tuberculosis, some of them are very susceptible indeed to
tuberculosis. Horses and dogs very rarely have tuberculosis.
Under certain conditions they may be made to take tuber-
culosis, and dogs particularly, when they take tuberculosis,
are liable to die of it quickly. A gentleman of rather eccentric
habits who had tuberculosis was particularly fond of dogs,
and it was his habit to have his dog in bed with him. He
killed four dogs with tuberculosis before he died himself!
(Laughter.) The dogs placed under these conditions took
tuberculosis and died quickly.
Scientific men have believed that there was a material
reason for these differences that was knowable and could be
discovered and explained, and work has been going on along
these lines now for a number of years for the purpose of
finding out the material elements that make up these differ-
ences in animals and these differences among men. And this
work is bearing fruit ; much is being discovered along this
line. You will remember that I told you the chemist was now
doing the principal work in bacteriology in finding out the
poisons produced. The chemist is also doing the principal
work in pathology in finding out the material elements that
go to make up these differences in susceptibility and im-
munity. The subject is in its growth form, not completely
grown, not completely understood. Only work has been
done that points out definitely the track of work in the future,
we may say. A man is exposed to small-pox, he takes the

disease, is sick; afterward he is immune. Why? The child
is exposed to measles and is sick ; afterward is immune.
Why? Now this is peculiar to the whole group of microbic
diseases with only a few exceptions, and it is especially pe-
culiar to those diseases that are self-limiting. Now, under-
stand what I mean by a self-limiting disease. A child takes
the measles we can confidently predict that that child will be
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