248 
A CONTRIBUTION. 
the blood, or the sub-cutaneous areola tissue; otherwise every 
vaccinated man and vaccine diseased cow would be a centre for 
many infections. This declaration entirely corresponds to the re¬ 
sults of the interesting experiments of Frolicli, Senfft, and Chau- 
veau. Frolicli always retained positive results after vaccine inoc¬ 
ulation of cows by punctures; but he could produce no variolse 
eruption when he introduced the vaccine by sub-cutaneous injec¬ 
tions, or by injections into the jugularis; but by the last experi¬ 
ments also the disposition to infection from vaccina was removed, 
as later inoculation gave negative results. Senfft received like 
results in that he received negative results from injecting vaccine 
lymph, pure or diluted, into the mammary vein or lymphatics of 
a calf; the same results followed like injections with the lymph 
from variola human a. Chauveau never saw a local or general 
eruption by cattle follow the injection of vaccine lymph into the 
veins; but although a negative reaction followed, the animals 
proved resistant to every successive vaccination. These experi¬ 
mentally proven differences are only, in my opinion, to be 
explained in one wa_y, and that is that the contagium of vaccine 
only finds the conditions favorable to its development in the supe¬ 
rior strata of the corium, while it probably suffers disturbances in 
the juices of the subcutis as well as in the blood. It would be of 
much interest to know definitely if this important fact , which to 
my knowledge only poseesses an analogy in the artificial disease 
(Dor chsenchinz), produced in consequence of the cutaneous inocu¬ 
lation by pleuropneumonia contagiosa , repeats itself by subcuta¬ 
neous or introveinous vaccinated men , and if such apparently re¬ 
sultless inoculations also gives protectiori against later vaccine 
infection or against variola humana. 
I can not pass by a very remarkable property of the conta¬ 
gium of variola humana and ovina; and this is, that inoculated, 
they both produce a far milder and far less lethal disease than 
when infection takes place in a natural manner. It is not at 
present to be decided whether this is owing to the manner the 
contagium gains access to the organism or not. 
A very important but little observed property of the conta¬ 
gium of vaccina is that it is active even when extensively diluted? 
