SCOTTISH METROPOLITAN VETERINARY MEDICAL SOCIETY. 501 
pestilences were sought for in, or attributed by the more learned to, 
cosmical or terrestrial phenomena over which man had no control. The 
doctrine of contagion was, it may be said, only very recently adopted 
with regard to the most markedly transmissible of these disorders, and 
it was far from being universally entertained by medical men or veteri¬ 
narians ; while even among those who most strongly favour it, it never 
appears to have been doubted that these diseases could be spontaneously 
generated through certain influences connected with atmospheric or 
telluric phenomena. But it must be confessed that, among veterinary 
surgeons in this country, up to a very late date, the doctrine of con¬ 
tagion was not received with much favour, if it was at all understood. 
Certain it is, that when we were invaded by two of the most serious of all 
the animal plagues, some forty years ago, their transmissibility from 
diseased to healthy animals does not appear to have been suspected. 
They were due to “ something-in-the air,” and as the action of this 
“something” could not be controlled, or its effects averted, these 
desolating pestilences were freely allowed to extend themselves every¬ 
where over the land, and to be carried to our colonies, where they con¬ 
tinue to ravage and destroy—a startling evidence of the results of 
unacquaintance with their early history and lack of perception on the 
part of those who then ruled in veterinary medicine in Britain. This 
lack of knowledge, and stern belief of “ something-in-the-air ” theory of 
disease, has been a source of terrible loss to the country during the 
period mentioned, and has done more to bring our agriculture to its 
present low ebb than almost any other cause which can be named. The 
ever-memorable invasion of cattle plague in 1865 affords a painful 
instance of the “ something-in-air ” and the “spontaneous-generation” 
fallacy, when the public was misled, and the necessary measures neg- 
glected, in order that these hobbies might be ridden. The lesson was a 
most severe, but it was a useful one, and it did more to abolish these 
fallacies, so far as they had reference to animal diseases of the contagious 
class, than anything else that could have happened. Nay, even human 
medicine reaped much benefit from the scourge, as it was most strik¬ 
ingly demonstrated how diseases which owe their existence to their 
contagious properties only may be checked or completely suppressed. 
Thus did public hygiene or state medicine receive one of its most potent 
arguments for ample recognition by the country, and the advantages of 
its application to the preservation of the health of mankind and animals 
obtain its strongest proof. 
I have alluded to the experimental method of investigation as that 
which has done medicine most service in abolishing the spontaneous 
generation notion of contagious diseases ; and it must be admitted that 
we owe it to the microscope to having provided us with the clearest and 
most satisfactory solution of the problem as to the cause of these dis¬ 
orders ; while the same instrument has lent invaluable aid in settling 
the spontaneous development question. 
To the microscope we are indebted for the establishment of the doc¬ 
trine of animate contagia, and for all the knowledge we possess as to 
the physical characteristics of these contagia. It is true that, some 
centuries ago, the most serious maladies of mankind were supposed to 
be due to minute organisms, which invaded the body and produced the 
disturbances that marked the course of the disorders. Thus (Scrulimum 
Physico Medicum C. Pestis dicitur , Rome, 1658), so long since as 1658, 
asserted that animacules were the cause of malignant and pestilential 
fevers, which differed in essence and symptoms according to the nature 
and venoms of these creatures. The celebrated Dr. Mead {ftxposito 
Mechanica Penenorum , 1749) entertained similar views with regard to 
LUI. 
