500 
THE SCOTTISH METROPOLITAN VETERINARY 
MEDICAL ASSOCIATION. 
SPONTANEOUS DEVELOPMENT OF CONTAGIOUS 
DISEASES. 
A Paper read by Mr. Fleming. 
Since the introduction of the experimental method of research into 
the study of disease, great and striking progress has been made in general 
and special pathology; and while human medicine has been benefited 
to a proportionate degree, veterinary medicine has largely shared in the 
advantages it has conferred. And perhaps in no branch of medicine— 
human or animal—have the benefits to be derived from the experimental 
method been so marked as in the investigations into the nature of those 
maladies we term “contagious,” “zymotic,” or “specific.” The spon¬ 
taneous origin of these disorders had, up to a comparatively recent 
period, been a generally accepted notion—indeed, an article of faith or 
doctrine which is, at least for some of these diseases, still held by 
many medical and veterinary practitioners. But the doctrine of spon¬ 
taneous origin or generation did not alone find disciples among medical 
men. Biologists and others believed that at least the more minute 
organisms could be generated or developed cle novo , when circumstances 
were favorable; and only a few months ago a lively discussion agitated 
the world of science as to whether microscopical germs might not be 
created in particular fluids, under certain special conditions. This was 
probably the last occasion on which we shall hear of spontaneous genera¬ 
tion ; for the admirably-conceived and well-executed experiments of 
Pasteur, but more especially those of our own countryman, Tyndall, 
appear to have set the question at rest for the present, if not for ever. 
But it was not until the adoption of the experimental method in bio¬ 
logical research, by men of genius and unwearied industry, that the 
question of so-called “ spontaneous generation ” obtained this definite 
solution, and the doctrinal notions generally held up to the other day 
only received so severe a blow that they may now be considered as 
dispelled and defunct. These notions were certainly losing their hold 
somewhat before the publication of the convincing demonstrations of 
the experimenters I have just alluded to; and it is possible that the 
increased intelligence developed by the rapid progress of scientific 
research during the first half of this century did much to bring about 
more reasonable opinions with regard to the generation of organised 
bodies. From the very earliest times the most absurd ideas prevailed 
with regard to the spontaneous creation of creatures—real or unreal— 
and of the largest dimensions and most complex organisation; and even 
so late as the time of Spallanzani, the notion of spontaneous generation 
was so fully and unreservedly believed in that it was popularly accepted 
that creatures so large and perfect as mice could be developed cle novo. 
But if the doctrine of spontaneous generation was in some respects 
absurd in the extreme, yet it produced no very harmful results in a 
general way ; and it was only when it asserted its sway in medicine that 
baneful effects were observed. The desolating scourges of mankind 
that swept over wide continents and carried off countless myriads of 
people, were ascribed, in the earlier ages of the world, to an irate deity 
or the vengeance of wrathful gods, whose murderous chastisements 
could only be averted by sacrifices, charms, and incantations. In more 
modern times, when superstition had less influence on the mind, these 
