92 REPORT—1896. 
transient duration, and the high hopes which had been inspired by Koch’s 
great reputation were dashed. It is but fair to say that he was strongly 
urged to publish before he was himself disposed to do so, and we cannot 
but regret that he yielded to the pressure put upon him. 
But though Koch’s sanguine anticipations were not realised, it would 
be a great mistake to suppose that his labours with tuberculin have been 
fruitless. Cattle are liable to tubercle, and, when affected with it, may 
become a very serious source of infection for human beings, more especially 
when the disease affects the udders of cows, and so contaminates the milk. 
By virtue of the close affinity that prevails between the lower animals and 
ourselves, in disease as well as in health, tuberculin produces fever in tuber- 
cular cows in doses which do not affect healthy beasts. Thus, by the 
subcutaneous use of a little of the fluid, tubercle latent in internal organs 
of an apparently healthy cow can be with certainty revealed, and the 
slaughter of the animal after this discovery protects man from infection. 
It has been ascertained that glanders presents a precise analogy with 
tubercle as regards the effects of its toxic products. If the microbe which 
has been found to be the cause of this disease is cultivated in appropriate 
media, it produces a poison which has received the name of mallein, and 
the subcutaneous injection of a suitable dose of this fluid into a glandered 
horse causes striking febrile symptoms which do not occur in a healthy 
animal. Glanders, like tubercle, may exist in insidious Jatent forms 
which there was formerly no possibility of detecting, but which are at 
once disclosed by this means. Ifa glandered horse has been accidentally 
introduced into a large stable, this method of diagnosis surely tells if it 
has infected others. All receive a little mallein. Those which become 
affected with fever are slaughtered, and thus not only is the disease pre- 
vented from spreading to other horses, but the grooms are protected from 
a mortal disorder. 
This valuable resource sprang from Koch’s work on tuberculin, which 
has also indirectly done good in other ways. His distinguished pupil, 
Behring, has expressly attributed to those researches the inspiration of 
the work which Jed him and his since famous collaborateur, the Japanese 
Kitasato, to their surprising discovery of anti-toxic serum. They found 
that if an animal of a species liable to diphtheria or tetanus received a 
quantity of the respective toxin, so small as to be harmless, and after- 
wards, at suitable intervals, successively stronger and stronger doses, the 
creature, in course of time, acquired such a tolerance for the poison as to 
be able to receive with impunity a quantity very much greater than 
would at the outset have proved fatal. So far, we have nothing more 
than seems to correspond with the effects of the increasingly potent cords 
in Pasteur’s treatment of rabies. But what was entirely new in their 
results was that, if blood was drawn from an animal which had acquired 
this high degree of artificial immunity, and some of the clear fluid or 
scrum which exuded from it after it had clotted was introduced under the 
