PROTECTIVE INOCULATIONS., 341 
mune animal, as a result of protective inoculations, upon which the 
immunity of these animals depends, is also a proteid, which they call 
antipneumotoxin. This they isolated from the blood serum of im- 
mune animals. By experiment they were able to demonstrate that 
the blood serum containing this protective proteid, when injected 
into other animals, rendered them immune; and also that it arrested 
the progress of the infectious malady induced by inoculating suscep- 
tible animals with virulent cultures of the micrococcus. When in- 
jected into the circulation of an infected animal, its curative action 
was manifested by a considerable reduction of the body temperature. 
The toxalbumin was obtained from filtered bouillon cultures of a viru- 
lent variety of the micrococcus of pneumonia, in the form of an amor- 
phous, yellowish-white powder. This was thrown down from the 
filtered cultures by means of alcohol, and again dissolved in water 
and reprecipitated in order to purify it. 
Issaeff (1893) as a result of his experiments has found that the 
virulence of this micrococcus can be greatly increased by successive 
inoculations in the peritoneal cavity of rabbits, and that after a series 
of ten or twelve such inoculations the blood of the infected animal does 
not coagulate and becomes extremely toxic. In order to obtain the 
toxins from this blood, Issaeff collects the blood of three or four ani- 
mals just dead in a sterilized vessel, and adds to this an equal volume 
of sterilized water containing one per cent of glycerin, made alkaline 
by the addition of a few drops of a concentrated solution of bicarbo- 
nate of soda. The mixture is sterilized by passing it through a Cham- 
berland filter. This liquid sometimes kills rabbits when injected into 
the circulation in the proportion of one per cent of the weight of the 
animal. When heated to 70° C. its toxic power is considerably di- 
minished, and a temperature of 100° C. neutralizes it completely. 
Emmerich (1891) has succeeded in immunizing rabbits and mice 
by the intravenous injection of a very much diluted but virulent cul- 
ture of the micrococcus. Other rabbits and mice were rendered im- 
mune by injecting into them material obtained from rabbits immu- 
nized with diluted cultures. The flesh of these animals was rubbed up 
into a pulp, and the juices were obtained by pressure through a piece 
of sterilized cloth. The bloody juice, after standing for twelve hours 
at a temperature of 10° C., was passed through a Pasteur filter and 
then served to immunize the animals referred to. 
Belfanti (1892) has succeeded in immunizing rabbits against the 
pathogenic action of this micrococcus by injecting into the circulation 
a filtrate obtained from the sputa of pneumonia cases. The viscid 
sputa mixed with an equal part of distilled water was kept on ice for 
