268 
Experiments on Anthrax conducted at 
body of a diseased animal, the poison so introduced multiplies 
and grows indefinitely, so that the whole quantity becomes 
poisonous ; and if a drop of this infected liquid is added to a 
new quantity of infusion, this in its turn acquires similar pro- 
perties, as may be readily proved by introducing it into the 
bodies of small animals, such as rabbits or guinea-pigs. In 
experiments of this kind the " grains " serve the purpose of a 
nursery or cultivating-ground in which the poison or virus 
may, as it were, be sown and propagated. VVe therefore call 
them " cultivation experiments." Any liquid or material which 
serves as a suitable soil for the growth and development of the 
virus may be called a " cultivation liquid." There can be no 
doubt that when disease suddenly breaks out in a previously 
healthy locality, as it did at Rigsljy, the meaning of the occur- 
rence is that the cattle were in some unknown way brought into 
contact with an infected "cultivating" material — a soil into 
which the seed of anthrax had been dropped, how we know 
not — which was suitable for its development. What this soil 
was in the case of the Rigsby outbreak cannot be stated. We 
have reason to be sure that it was not the water which the 
animals drank, and have no ground for concluding that the 
particular " grains " on which they were fed were infected. 
With reference to the origin of the outbreak of anthrax it is 
to be borne in mind that the anthrax virus exists in two dis- 
tinct forms — one in which it is latent, and may remain for 
years inactive, although capable of being called into activity 
by suitable conditions ; the other, in which it grows and multi- 
plies, as it does in the body of the infected animal. It is known 
that, in general, infected liquids, such as the blood or tissues of 
diseased animals, are dangerous only when fresh, losing their 
specific properties as soon as decomposition begins. But when 
the material has arrived at a certain stage of maturity, it 
acquires the power, if preserved from destructive influences, of 
retaining its virulence for years. I possess a specimen of blood 
which was taken six vears ago from a bovine animal, and was 
found, when recently tried, to be still virulent.* 
I. Inoculation of Small Animals with Anthrax Blood. 
Feb. \%th. — The fresh blood from the spleen of a heifer that 
died of splenic fever at Rigsby on the night of the 17th was 
* Why the anthrax poison is in one state perishahle, in another permanent and 
resisting, is fairly understood by scientific men. The reader who is curious on 
the subject will find information in Prof. Tyndall's ' Fragments of Science ' (vol. ii. 
p. 282), or in my lectures on ' Infection," delivered at the University of London in 
1878, and reported in the 'British Medical Journal' for January and February, 
1S78. 
