SERUM THERAPEUTICS IN RESPECT TO TUBERCULOSIS. 801 
What a vision these latter facts seem to unfold ! By some 
similar process it may be found possible to render our herds immune 
to tuberculosis, and their milk, instead of an ever-present danger, a 
potent means of fortifying delicate persons and children against that 
deadly scourge ! 
“ How is it possible,” as Professor Koux says, “ to avoid devoting 
all our attention to these antitoxines, which appear to be scientific 
remedies for two of the most serious diseases so feebly combated by 
empyrical means until now ?” And how, I would venture to add, is it 
possible to avoid turning a hopeful glance towards other terrible 
maladies, such as leprosy and tuberculosis, to see what promise these 
extraordinary revelations of serum therapeutics may hold for them 
also ? 
It may be objected in limine that diseases of the kind mentioned 
are intrinsically different from those that have been so successfully 
dealt with : from diphtheria and tetanus on the one hand, in which the 
toxines are absorbed from a local focus, but the bacilli themselves do 
not pervade the organism ; and such diseases as anthrax, on the other 
hand, where the living bacilli themselves swarm in the blood and 
internal organs. But the very fact of the success of serum thera- 
peutics in two such dissimilar conditions seems to warrant the hope of 
a like success in diseases which have points of resemblance to both. 
In regard to tuberculosis, it is well known that there are great 
differences in susceptibility in different species of animals, and even 
amongst individuals of the same species, as is notorious in the case of 
mankind. On what do these differences depend ? Probably, I would 
suggest, leaving out of consideration for the present possible differences 
in the phagocytic power of the amoeboid and fixed cells, on the amount 
of toxine neutralising substance (tubercle anlitoxine) preseut in the 
blood, or on, or combined with, capacity of the organism to generate 
such substance. The latter supposition seems to offer a clue to the 
benefit sometimes derived from Koch’s tuberculine in incipient 
tuberculosis — i.e., in cases where the organism is still capable of 
responding to the toxine tuberculine by an increased production of the 
antitoxic material. 
If this be the true explanation of differences in susceptibility to 
tuberculosis, it would seem, judging by the analogy of the cases of 
tetanus and diphtheria, that if an animal having a high degree of 
natural resistance were repeatedly injected with the toxine of the 
tubercle bacillus it would tend to bring about a great development of 
the antitoxic or neutralising principle, and the scrum of the animal 
so treated might perhaps be fouud of therapeutic value in the treat- 
ment of the disease. It is, however, open to question whether an 
animal having a strong natural resistance is necessarily capable of 
generating more of the antitoxic principle than one having a less 
natural resistance. A priori it would seem probable. 
With a view of testing the validity of these ideas, I have lately 
made an experiment (on a very small scale), an outline of which may 
be of interest, not perhaps on account of any great value or con- 
clusiveness of the experiment itself, but as an illustration of the kind 
of way in which, I venture to think, our present knowledge seems to 
lead us to look for a scientific method of combating tuberculosis. 
