.TAMES LAW. 
infection is often slower. Manifestly it is carried by the flowing 
swill from the higher to the lower end of the trough, and infects 
the susceptible animals in its course. Here again there is the 
rapid conveyance of the contagion through the medium of the 
food and independently of all actual contact with the living dis¬ 
eased animal. 
One case more, drawn from the enemy’s camp. Dr. Francis 
Bridge, whose great experience and sound judgment are endorsed 
by Dr. Gadsden, relates the infection with lung plague of one 
herd by the use of a drinking horn which had been used a short 
time previously for drenching lung plague victims in another herd. 
This case is further attested by Mr. Tlios. J. Edge, Secretary of 
the State Board of Agriculture in Pennsylvania. Here then the 
horn , soiled with the infecting mucus , is the medium of contagion, 
there having been no actual contact. 
That cattle have escaped the disease though put in infected 
stables, proves nothing at all, or, if it proves anything, it proves 
too much. So of the exposure of cattle to contact with the dis¬ 
eased lungs after they have been removed from the body. 
To give such instances any value two things must be detnon- 
trated: first, that the lungs of this particular animal contained 
the virus in a potent state, and second, that the animals brought 
into contact with this lung were animals susceptible to this infec¬ 
tion. 
Many individuals are not susceptible to a given infection, and 
many insusceptible at one time are found to be susceptible a short 
time after. I have made an unsuccessful inoculation of vaccina 
direct from the vesicle, though the virus proved extra active on 
the other cases vaccinated at the same time. I have a few months 
later successfully vaccinated the previously refractory subject, and 
have seen him undergo quite a severe attack. If I had inoculated 
this one subject only the first time, would it have been fair to 
blame the virus ? Assuredly not. The scientific spirit says with 
Professor Walley, “ One swallow does not make a summer.” 
Muc h more, the absence of a swallow does not make a winter. 
If all members of a given genus were equally open to contract 
a contagion , we would be made acquainted with epizootics of a 
very different type, and a fatal disease like lung plague or rinder* 
