Foot-and-Mouth Disease. 
449 
all the subjects within reach of the infection are indiscriminately 
included. 
Foot-and-mouth disease is no exception to this rule ; since 
its introduction into this kingdom in 1839 it has mani- 
fested itself at certain periods in the form of an epizootic, 
ravaging extensive tracts of country, and having exhausted its 
force on the susceptible animals within its reach, has declined 
until it reached a minimum. Sometimes the affection assumed 
the character of an enzootic, but in these instances there was 
always a reasonable explanation of the limited spread of the 
disease, in the circumstances of the locality ; either the cattle 
population was small, or the district was out of the way of cattle 
traffic, and the affection having attacked the animals in the 
place, ceased for want of new material. 
In reference to the direction which epizootic diseases take, 
there is a general belief that they always proceed westward, and 
there is some evidence in support of this view ; but so far as 
foot-and-mouth disease, and indeed all other infectious maladies 
of stock are concerned, the rule has no existence in this kingdom. 
Railways radiate in all directions, and it may be assumed with 
safety, that from the centres of disease the virus will be conveyed 
wherever the lines of cattle traffic extend. 
Granting the influence of susceptibility in modifying the pro- 
gress of contagious diseases, the chief cause of their spread is 
the movement of diseased and infected animals in the ordinary 
course of trade ; and very curiously this practically vital point in 
sanitary law has received the least attention, not from the legis- 
lature, but from the stock-owner. 
If a critic wished to secure attention to his remarks, he would 
carefully avoid such a commonplace statement as that which 
refers the extension of disease to the movement of infected ani- 
mals, and proceed to a discussion of the possibility of spon- 
taneous origin, the prevalence of minute spores of fungi, 
atmospheric changes, and indirect conveyance of the poison by 
flies, birds, and the smaller quadrupeds, which, if not themselves 
liable to be attacked with the disease, may carry on their feet, 
or other parts of their bodies, the excreta from diseased animals. 
Full weight may be allowed for all the mischief done by the 
indirect conveyance of infection by men, animals, or substances 
which have been in contact with diseased beasts, or with the pro- 
ducts of the disease ; but still the fact remains, that the malady 
is kept in a state of activity mainly by means of the living 
creatures which are suffering from it. During the inquiries which 
have at different times been instituted in the country for the 
purpose of determining the causes of the extraordinary prevalence 
of foot-and-mouth disease in certain districts, the fact above 
