TUBERCLE BACILLI IN MILK, ETC. 33 
white, and dry, later spreading over the wliole surface and becoming yellow or copper-coloured. 
On potato a luxuriantly-growing, moist, grey layer is formed. In gelatine growth proceeds very 
slowly at ordinary room temperatures, colonies becoming visible on the 3rd day. In broth, and 
especially in glycerine broth, growth is rapid, forming in 2 or 3 days a folded membrane on the 
surface, the broth remaining clear, the culture closely resembling that of bacillus tuberculosis. 
Broth cultures are distinguishable from those of bacillus tuberculosis by their characteristic odour, 
being unpleasant and ammoniacal ; that of bacillus tuberculosis being agreeable and resembling the 
odour of flowers. A small quantity of indol is formed in broth cultures, which is not so in bacillus 
tuberculosis cultures. Milk is not coagulated, and on tiie surface is an abundant yellowish-red 
layer which clings firmly to the glass. On albumin-free colourless media a growth appears in 2 or 
3 days, becoming in 10 days a thick yellow folded membrane ; bacillus tuberculosis in the same 
time on such media forming a thin layer just covering the surface and just beginning to fold. 
The presence of fat in these bacilli can easily be demonstrated as in the case of bacillus 
tuberculosis. 
Pathogenic Properties of Bacillus Pseudo-tuberculosis 
The following are the post-mortem appearances observed in a Guinea-pig killed three or 
four weeks after intraperitoneal injection of butter containing the bacillus pseudo-tuberculosis. 
There is a slightly distended abdomen ; also peritonitis, with adhesions varying in nature from 
delicate fibrinous bands to firm connective tissue. The peritoneum and mesentery are studded 
with nodules. The mesenteric glands are swollen and may contain purulent or caseous matter. 
The liver is covered with nodules and patches which may be raised above the liver substance or 
may penetrate into the liver parenchyma. The spleen is sometimes only enlarged, at other times 
thickly studded with nodules. The kidneys show yellowish patches. The lungs are covered 
with small transparent nodules which do not penetrate into the lung tissue. The sternal 
lymphatic glands are swollen, but show no caseation. Numerous bacilli can be demonstrated in 
these lesions. Many animals after injection show considerable signs of illness during the first 
14 days with diminution in weight and then recover. Pure cultures of this bacillus are 
only pathogenic for Guinea-pigs (but not always) ; Rabbits and white Mice are immune. After 
intraperitoneal inoculation of Guinea-pigs some die in from 4 to 8 weeks with considerable 
emaciation and show the following post-mortem appearances ; others survive. At the seat of 
inoculation there is a purulent infiltration containing the characteristic bacilli ; also peritonitis, 
varying in intensity from a flocculent fibrinous exvidation to strong connective tissue adhesions, 
The mesentery is studded with small nodules ; the glands are enlarged but not caseating ; there 
are patches on the liver, and miliary nodules throughout an enlarged spleen. The thoracic cavity 
and organs are often almost exempt from lesions. Infected animals do not react to tuberculin. 
Histologically the nodules in the liver and spleen consist of a collection of lymphoid elements 
with but very few epithelioid and multinuclear cells. The bacilli are found in the middle of a 
young nodule, towards the periphery if caseation has commenced. The typical giant cells of 
tuberculosis do not occur. More often — especially after inoculation with butter containing the 
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