OBSERVATIONS ON THE LUNG PLAGUE OF CATTLE. 619 
territory, it seems reasonable that this bulletin should set 
forth a summary of what has been accomplished, and what lessons 
have been learned from the experience. It must, however, be 
premised that no means were provided for experimental observa¬ 
tion, so that questions of the deepest interest to the pathologist 
and epidemiologist have had to lie unaffected by such crucial 
tests as the experimentalist alone can apply. In some respects 
this is to be regretted, as doctrines, which are now but the 
deductions of empirical observations, might have been placed on 
an irrefragable basis, and certain fields of pathological science 
might have been illuminated with a clearer light. 
Yet the observations inseparable from the daily application of 
suppressive measures are far from being unimportant, and in 
many respects the results obtained are no less conclusive than if 
they had been the outcome of the most carefully devised experi¬ 
ment. The width of the field under observation, so far exceed¬ 
ing what could have been subjected to experiment, served to 
give a conclusiveness to obvious causations and results that 
appeared unvaryingly for an indefinite number of times in 
succession, which could not have been obtained by a limited 
number of experiments, liable as these are to be invalidated by 
the introduction of an unsuspected disturbing element. 
Question of the Generation de novo of Lung Plague.— 
This is the fundamentally important question with reference 
to the possibility of the final extinction of this disease here or 
elsewhere. If the malady can and does originate on this Conti¬ 
nent no present outlay in money, and no effort for its present 
extinction, can give us any guarantee of permanent immunity. 
After we have rooted out the last existing contagious germ, new 
germs will still continue to appear at more or less frequent 
intervals, and in more or less remote localities, demanding in 
every such case the repetition of the work of the outlay and 
suspense that have already repeatedly taxed the energies of the 
nation. And if such a spontaneous generation of the germs be 
possible, new spontaneous outbreaks of the disease must become 
increasingly common as our waste lands become more uniformly 
settled, as our farms become more fully and carefully tilled, and 
as the herds of cattle become more numerous. When our 
present stock of cattle shall have been doubled, we shall have 
just double the number of such outbreaks; when trebled 
quadrupled, and quintupled, so will the newly developed germs 
and infected localities be three; four, or five times as many as at 
present, and the question might well arise whether the nation 
could afford to continue the suppression of such an uncertain, 
intangible, and unconquerable enemy. 
But if we can demonstrate that this plague has never been 
