ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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rendered insensitive to tlie virus provided the initial doso be very small. 
By this method they succeeded in rendering two pigeons and one dog 
refractory, and evolved the following facts: — The blood-serum of the 
dog when mixed with filtered tetanus cultivation destroyed its toxicity 
completely, even when the quantity of serum was very small, and the 
duration of contact very short. Subcutaneous injection of this serum 
rendered another dog immune to the tetanus virus, and similar results 
were obtained when white mice were injected. If, however, the dose 
was very large (1 ccm.), these animals died. Rabbits and guinea-pigs 
also succumbed under like conditions. The pigeon’s blood-serum gave 
similar results. It is noted that injection of blood-serum after inocula- 
tion of the virus failed to prevent the appearance of tetanic symptoms. 
Anthrax Vaccination.* — Mdme. O. Metschnikoff, when examining 
the effect of anthrax vaccines i. and ii. on sheep, found that the bacilli 
were almost always only at the injection spot, were surrounded by 
leucocytes, and in a degenerate condition ; only a few bacilli being free 
and of normal appearance. Moreover, the aqueous humour of sheep 
which had undergone vaccine-fever, did not inhibit the growth of the 
spores of i. and ii. vaccines, or of virulent anthrax. Consequently it 
contains no bactericidal matter. Experiments on rabbits gave quite 
analogous results. 
The vaccine-protection is therefore brought about by the products of 
the bacilli being diffused through the body, and the destruction of the 
bacteria is effected by phagocytosis. 
Protective inoculation doubtless consists in the cellular elements 
becoming habituated to the toxic products of the bacteria. 
Germicidal Substance of the Blood.j — Prof. M. Ogata has isolated 
from the blood of dogs and fowls a substance which renders immune to 
anthrax and mouse-septicaemia animals susceptible of those diseases, and 
the author regards this substance as a ferment contained in the blood of 
the immune animals. The ferment has the following properties. It is 
readily soluble in water and glycerin, but insoluble in alcohol and ether. 
Its efficiency is not impaired by the action of weak alkalies, but is 
entirely suppressed by carbolic and hydrochloric acids. In the presence 
of the digestive juices, and if heated up to 45° C., its action is destroyed. 
The ferment possesses not only immunizing but also disinfecting pro- 
perties, and mixed with glycerin retains its efficiency for a long time 
without any notable change. It does not appear to possess the power of 
converting fibrin into pepton, or starch into sugar. 
In addition to the foregoing characters, this substance also possesses 
the power of inhibiting the growth and development of the cholera and 
typhoid bacilli, a fact which induces the author to think that the dis- 
infecting action of the blood may be due to this ferment. 
The ferment is prepared in the following manner. To one part of blood 
or blood-serum are added 10-15 parts of a mixture of absolute alcohol and 
ether (equal parts). After filtration the precipitate is dried (on the 
* Ann. de l’lnstitut Pasteur, 1891, p. 145. See Centralbl. f. Bakteriol. u. Para- 
sitenk., ix. (1891) pp. 738-9. 
t Centralbl. f. Bakteriol. u. Parasitenk., ix. (1891) pp. 597-602. Cf. this 
Journal, ante , p. 237. 
