BACILLUS ENTERITIDIS OF KLEIN 133 
up to 8o°C. to kill non-sporing organisms. The tube is then cooled and placed with a 
certain quantity of a fresh solution ot pyrogallic acid and caustic potash in a Buchner's 
cylinder, tightly corked, and incubated at 37 C. In from twenty-tour to forty-eight 
hours, if the bacillus is present, a most striking and characteristic change occurs. The 
milk is ' curdled with copious evolution of gas, the spongy curd floating in a fairly 
clear transparent whey;' the reaction is acid, with a smell of butyric acid. Micro- 
scopical examination reveals multitudes of bacilli in the form of 'rods and cylinders,' 
which stain by the method of Gram. 
The virulence of the organism is classed as normal by Dr. Klein, it the 
subcutaneous inoculation of one cubic centimetre ot whey from a recently changed 
milk culture into a guinea-pig weighing from 20C-300 grammes is fatal in about thirty 
hours or less, the animal dying with ' severe haemorrhagic oedema and gangrene of the 
subcutaneous tissues, spreading widely from the point of inoculation.' The virulence 
of the organism is diminished it the guinea-pig dies slowly, or recovers with extensive 
sloughing of the skin in the neighbourhood ot inoculation. Lastly, if the only 
result of inoculation is a transient swelling without subsequent necrosis, the milk 
culture contains the bacillus of Botkin ; an organism which is said to resemble the 
bacillus enteritidis sporogenes in almost every respect save one, viz., that its cultures 
are non-pathogenic when inoculated subcutaneously into guinea-pigs or rabbits. 
The only other anaerobic sporing organism with which bacillus enteritidis 
might be confounded is the bacillus of malignant oedema. This organism, as Klein 
points out, does not stain by Gram's method, and does not produce in anaerobic 
milk cultures, or when inoculated into guinea-pigs, the changes which are characteristic 
of bacillus enteritidis sporogenes.* According to Klein, the presence of the bacillus 
enteritidis is proved if an anaerobic cultivation of its spores in milk produce certain 
reactions, and if the resulting whey exerts certain definite pathogenic effects when 
inoculated subcutaneously into the groin of a guinea-pig. Microscopical examination 
of the organism and subcultivation is not necessary. 
I have, however, during observations on the spores of bacillus enteritidis 
obtained from various sources, examined microscopically as a matter ot routine a 
large number of typical milk cultures, and in every instance detected, usually in pure 
culture, the characteristic bacilli which stained by the method of Gram. 
Subcultivation of bacillus enteritidis, like other anaerobic organisms, on solid 
media, is unsatisfactory. Although I have obtained in blood serum, glucose agar, and 
glucose gelatin, pure colonies of the bacillus, the usual result of transplantation into 
milk is not a ' typical ' culture, but one deficient in whey and gas formation, and 
containing many spores. ' This ability to cause atypical change in milk occurs,' 
according to Klein, 'sooner or later to bacillus enteritidis from any given source. 'f 
* Medical Officer's Report, Local Government Board, 1897-98, pp. 227-229. 
t Medical Officer's Report, Local Government Board, 1S97-98, p. 224. 
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