636 
RECIPROCAL INFLUENCE OF ANIMALS. 
one set of men shut up for some time together was poisonous 
when inhaled hy others (and perhaps more so, if the men are 
of different races). 
It has been believed for a long time that young people will 
lose their health, and even die, if compelled to associate and 
sleep with aged individuals. Many apparently authentic 
cases of this kind have been adduced.* 
Among the lower animals, as I have already stated, the 
observations have not been so numerous, or perhaps so 
striking, as in mankind. With them as with the human 
species, however, it is undoubtedly a fact that, until the 
introduction of certain species of creatures, or even varieties 
of the same natural family, particular maladies were unknown 
to the indigenous races; and that as soon as these new 
arrivals appeared, though no symptoms of disease could be 
detected in them, yet affections of an oftentimes deadly 
nature, and frequently epizootic in character, have been deve¬ 
loped. Some of these maladies would, doubtless, in time all 
but, if they did not entirely, exterminate the native breeds— 
just as many savage races of men on the American, Asiatic, 
African, and Australian continents have been decimated after 
their having been in contact with white people—leaving the 
imported ones in possession of the country. 
What better proof of the truth of this assertion could we 
have than in the cattle plague—a disease which, in the 
Steppe bovine race, sometimes appears in such a mild form 
as to be nearly, if not quite, imperceptible; and yet the intro¬ 
duction of the animals among the herds of other, and parti¬ 
cularly western countries, is attended with the greatest risk 
of a fearful mortality, from which the invading troops are 
largely exempt. Hussian authors, as Lepechin and Jessen, 
have certainly stated that the cattle plague is primarily deve¬ 
loped in the migrating droves, and several other authorities— 
amongst them Paulet, Huzard, and Rawitsch—have professed 
the same opinion. They quote repeated observations which 
show that cattle which left Russia or Hungary in perfect 
health and good condition were only attacked with the disease 
when they had been some time on the way, or even when in 
Germany or France. Hurtrel d’Arboval declares that a Hun¬ 
garian ox, deprived of salt and heated by a forced journey, is, 
perhaps, the animal most to he dreaded amongst its own 
species. But though these fortuitous circumstances of hunger 
and fatigue are laid much stress upon by these veterinarians, 
there are, nevertheless, men of high repute who believe that 
such cattle have infected those of other countries, particularly 
* Stark, ‘ Pathologie,’ vol. i, p. 363. 
