ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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microbes. (3) Destruction is followed by revival, a fact which proves 
that the microbes have adapted themselves to their new environment. 
(4) The bactericidal power is not a property peculiar to the blood 
while in the vessel, but appears only after extravasation. (5) The bac- 
tericidal power is not correlated with the animal’s resistance ; thus 
rabbit’s blood is as bactericidal as dog’s blood to anthrax, yet the recep- 
tivity is quite different. 
In these experiments the authors used B. coli communis and B. 
anthracis, and their conclusions are entirely favourable to the view held 
by Buchner and others that the body-juices play a considerable part in 
the defence of the organism against infection. They are antiseptic 
solutions, in fact. 
Besides controverting the foregoing objections, two new views on the 
subject are put forward: — That there is an antagonistic action between 
the bactericidal substance and the microbic poison ; and that there is a 
reaction of the organism during the infection, even when this is inevitably 
fatal. 
Acquired Immunity to Pneumococcus.* — M. B. Issaeff, who has 
been making some experiments on rabbits with Pneumococcus , finds 
that phagocytosis plays an important part in the preservation of rabbits 
against this micro-organism. The author’s object was apparently to 
ascertain whether there was any basis for the bactericidal, the attenua- 
tion, or the antitoxic theories of immunity to Pneumococcus. According 
to the bactericidal theory the humours (body-juices) and blood-serum of 
the vaccinated organism prevent the development of the microbes, which 
perish in the humours. The attenuation theory, while admitting the 
possibility of microbes developing in a vaccinated organism, asserts that 
the microbe loses its pathogenic properties owing to the influence of the 
vaccinated serum, and in this way become harmless to the organism. 
The antitoxin theory would explain acquired immunity to Pneumococcus 
by the property the serum of vaccinated animals possesses of neutralizing 
the toxines of Pneumococcus. As the experiments showed that these 
three theories received no support from the facts, the leucocyte is pro- 
nounced to play the chief part in this acquired immunity. The general 
conclusions of the author are that : (1) The toxins of the Pneumococcus 
(Fraenkel) excite a more energetic reaction in rabbits previously 
vaccinated with this microbe than in the control animals. (2) The blood- 
serum of rabbits vaccinated against the Pneumococcus, though possessing 
therapeutic properties, is not endowed with any antitoxic power. 
(3) The serum of vaccinated rabbits does not possess the property of 
attenuating the virulence of the Pneumococcus. (4) The Pneumococcus 
when cultivated in the serum of vaccinated rabbits does not lose the 
power of producing toxins. (5) The Pneumococcus when inoculated on 
a vaccinated rabbit preserves its pathogenic properties for about 
18 hours, and its vitality for about 48 hours after inoculation. (6) In 
the acquired immunity to Pneumococcus phagocytosis plays a most 
important part. 
Presence of Bacterium coli commune and Bacillus typhosus in 
Drinking-W ater.f — M. E. Malvoz, who examined the water from 
* Ann. Inst. Pasteur, vii. (1893) pp. 260-79. 
t Mem. Soc. d’Hygiene et de Salubrite Pub. de Liege, 1892. See Centralbl. f. 
Bakteriol. u. Parasitcnk., xiv. (1893) p. 69. 
H 2 
