650 INFLUENCE OF CHOLERA ON THE LOWER ANIMALS. 
ments, that it is obviously impossible for individual practi- 
tioners, who have at their disposal only a limited amount of 
time and opportunities, to make and record observations or 
experiments on all the topics which I am about to mention. 
But it is in the power of the provincial practitioners of 
Britain to be of great service, not perhaps so much by per- 
sonally observing facts, as by recording those observed by 
others. They might do a great good, at a trifling expense 
of time or trouble, by directing to this subject the attention 
of non-professional persons, whose duties or tastes lead them 
constantly to observe the habits and diseases of the lower 
animals, especially such as are domesticated, and by record- 
ing the results of their experiences, whether positive or 
negative. To indicate the kinds or classes of persons to 
whom I here allude, I need merely mention dog-breakers, 
cattle-breeders, sheep-dealers, graziers, farmers, grooms, 
poultrymen, and the like. Such a record, like a register of 
meteorological observations, though apparently uninteresting 
or unimportant in detail, could not fail to prove of the ut- 
most value in the aggregate, whatever the nature of the 
general results or conclusions to which it pointed. For it 
must ever be borne in mind, that negative facts in science 
are often of equal importance with those which are positive 
— a knowledge of what is not, frequently most materially as- 
sisting us in arriving at a knowledge of what is. Let not an 
observer or recorder be prevented from giving publicity to a 
single fact on account of its apparent insignificance; in an 
investigation of such a nature, every well ascertained fact 
has its positive and relative value. While some facts are of 
such a kind that they may be, with propriety and safety, ob- 
served by non-professional, and even by totally uneducated 
persons, and may be accepted without further evidence than 
the testimony of an informant, others must be tested by ex- 
periment, and not a few ought to be sifted by scientific 
experts, acquainted wdth the details of modern histology, 
chemistry, and pathology, and conversant with all the bear- 
ings of the subject. I would suggest that particular points 
be selected for investigation, according to the opportunities 
or inclinations of individual members of associations or so- 
cieties, whose researches might converge towards a common 
aim. Our medical societies, especially such as devote atten- 
tion to the natural history of epidemics, might do much 
service to science by taking up this inquiry officially. Such 
a mode of following out the subject, is most likely to be fol- 
lowed by beneficial results. 
[To be continued .) 
