846 
THE VETERINARIAN, DECEMBER 1, 1880. 
Ne quid falsi dicere audeat, ne quid veri non audeat.— Cicebo. 
INFECTION AND RECEPTIVITY. 
Pathological inquiries are year by year tending more 
and more definitely to the conclusion that infective matter is 
a material thing, and not a mere property of morbid pro¬ 
ducts, and the directors of future investigations must 
necessarily be in the way of identification of the material 
which is proper to each form of infection. This result 
once gained, the isolation and destruction of the infec¬ 
tive material would, in all probability, present no serious 
difficulties. 
In direct relation to the power of infective matter stands 
that state of system which enables the infective matter to 
act, a state which may be termed receptivity. How 
different this state is in different individuals of the 
same family even may be demonstrated by very simple ex¬ 
periments. We need only refer to a few well-known dis¬ 
eases to establish this proposition beyond question. Foot- 
and-mouth disease finds a receptive state of system for its 
special infective matter in a large number of animals of 
different species ; others, such as the members of the equine 
family and the carnivora, are incapable of being acted upon, 
Pleuro-pneumonia of cattle appears to meet with the recep¬ 
tive state only in the ox tribe, and among them there are 
many instances of insusceptibility to the influence of the 
virus, while the receptivity to the poison of anthrax would 
seem to be almost universal. 
Under varying climate, and other conditions which are 
not well understood, the degree of susceptibility to infective 
matter differs much among animals which are known to be 
susceptible to the influence of a particular virus. This 
peculiarity is evidenced in outbreaks of many infectious 
maladies, foot-and-mouth disease among them. This affec* 
tion, under some circumstances, progresses slowly, and the 
