664 
E. ROUX, L. MARTIN AND A. CHA1LLOU. 
means of a large trocar, blood has been removed more than 
twenty times, the vein remaining as supple and as permeable as 
on the first day. Their immunizing power is in the neighbor¬ 
hood of 100,000 and it would be easy to increase it. 
Our immunized horses are cab-horses from six to nine years 
old, who are feeding well, and have no organic disease, espec¬ 
ially of the kidneys, and which have been discarded from work 
for injuries to their legs, hirst of all, it has been ascertained 
that they do not react to mallein, and hence are free from 
glanders. 
In order to immunize our horses we inject gradually increas¬ 
ing doses, under the skin of the neck or back of the shoulders, 
of a toxine of a great activity and able to kill, in doses of 
I-1 o c.c. in 48 hours', a guinea-pig weighing 500 grammes. In 
two months and twenty days, one of our horses received more 
than 800 c. c. of toxine, without manifesting anything but a 
transitory local oedema and a rise of temperature of i° C., 
(1 4-5 0 F.,) on the evenings after he had received a copious 
injection. 
On the same day that this horse was bleed for the first time 
(87th day of the experiment), he bore an introduction in the 
jugular of 200 c. c. of diphtheritic toxine without being incom¬ 
moded by it. In the evening he had a slight fever, but did not 
lose his appetite. 
The serum so removed has a preventive power superior to 
50,000, i. e., a guinea-pig proves resistant to an inoculation of a 
half a cc. of very recent and violent diphtheritic culture if, 
twelve hours before, he has received a quantity of this serum 
equal to the 1-5,000 part of his weight. A mixture of 1-10 cc. 
of this serum and one cc. of toxine does not cause local oedema 
in the guinea-pigs under whose skin it is injected. 
The horse is therefore the best animal that can be employed 
in the preparation of the anti-diphtheritic serum. His indiffer¬ 
ence to the toxine of diphtheria spares the experimenter many 
difficulties that are experienced with more sensitive animals. 
When the horses have been brought to a sufficient degree of 
