7 52 INTRODUCTORY LECTURE ON HIPPOPATHOLOGY. 
the patriarchs of the Old Testament, seem to have paid 
as much attention to the principles of hygiene, or the pre¬ 
servation of animal health, and to have been as successful in 
their application of these, as they were to certain important 
conditions associated with the physiology of reproduction. 
Jacob, we are told, by his knowledge of the influence 
which the sight of certain external objects possesses on 
animals during conception and the early stages of gesta¬ 
tion, in determining peculiar conditions of the future pro¬ 
geny, obtained by means of his party-coloured or peeled 
rods of green poplar, chestnut, and hazel, placed in the 
gutters before the breeding cattle, a much larger proportion 
of party-coloured offspring—his stipulated price—than other¬ 
wise he would have obtained. W e are not, however, made 
acquainted with the means through which he obtained the 
other results, which he tells Laban had been achieved, viz. 
that during the twenty years he had been with him neither 
the ewes nor the she-goats had cast their young. 
From the earliest periods the most ordinary observers of 
facts and occurrences have noted the obvious separation of 
animals into strong and weak, healthy and diseased, and the 
unvarying certainty with which these have propagated in 
their offspring their own individual peculiarities, good or 
bad, the establishment of undeviating hereditary conforma¬ 
tion and predisposition, in obedience to the operation of the 
universal law of “ like producing like.” 
In addition, however, to this inherent and independent 
predisposition to contract disease, or even its occasional 
appearance in both strong and weak, from the operation of 
accidental causes, we may learn from the records of the past 
which have been handed down to the present, sometimes as 
detached and incidental information, more rarely as a con¬ 
cise and connected history of some dire calamity, thereby 
showing us that the early fathers of our race were not alto¬ 
gether ignorant of another great group of diseases, which 
is ever referred to under the generic term of plague or 
murrain. 
Now, although we may not find in these early periods any 
well-sustained attempts to separate these diseases into what 
appears to us well-defined subdivisions, of local, or enzootic 
or endemic , and general, or epizootic or epidemic , the true 
plague of men and of animals; although they may not have 
observed that these in their origin and distribution are 
essentially different, the one originating from some accidental 
cause, some extraordinary telluric or meteorological ox dietetic 
influence ; and although extensively distributed as if from 
