338 
r>. E. SALMON. 
Fortunately, the microscopist of to-day lias the means of ac¬ 
curately determining the nature of such granules—this is accom¬ 
plished by their cultivation in suitable media. Pasteur demon¬ 
strated that these granules might be cultivated in a liquid ob¬ 
tained by simmering the muscles of fowls in water and afterwards 
filtering to transparency and sterilizing by heat; this I have con¬ 
firmed by long-continued and careful experiments . 
Can we be certain, however, that the organisms which we are 
cultivating really existed in the blood of the fowl while circulat¬ 
ing in the veins, or may they not have gained entrance from the 
air ? This objection is more pertinent than many imagine, for, 
notwithstanding assertions, very few persons, taking the world 
over, have made pure cultivations from virulent liquids. Klein 
believes that he has done this with the virus of the disease which 
he calls pticuvio-enteritis of swine, and which is so well known in 
this country as hog cholera; but my own investigations do not 
confirm this, for I have always obtained by cultivation an entirely 
different organism, being the one which Klein himself discovered 
in the tissues of affected animals, and which he was led to discard 
by what I am forced to consider most imperfect cultivation ex¬ 
periments. Even Drs. Wood and Formad are constrained to 
admit that in their cultivation of the supposed virus of diphtheria 
if the temperature was varied, a different organism frequently ap¬ 
peared.* These gentlemen selected the cultivation apparatus 
which misled Klein, and which, to say the least, is hardly suited 
to investigations of this delicate nature. 
The writer has used an apparatus of his own, which will be 
fully described in his report to the Department of Agriculture of 
1881, and which in his hands has given the most complete satis¬ 
faction. Instead of using one or two drops of liquid for a culti¬ 
vation medium, the usual quantity is half an ounce; and this has 
been increased for special purposes to a quart. A small fraction 
of a drop of virulent blood added to such an apparatus, with suit¬ 
able precautions for excluding atmospheric bacteria, will cause 
Drs. II. C. Wood and H. F. Formad. Report on Diphtheria .—Supplement 
No. 17, National Board of Health Bulletin , p. 6. 
I 
