2i6 MILK AND THE PUBLIC HEALTH ch. xm 



and dissolved. In addition the majority of the other bacilli 

 present are dissolved, while tubercle bacilli resist the solvent 

 action. The use of antiformiu has been found valuable in the 

 detection of tubercle bacilli in sputum, and it should be of 

 value in the examination of milk. 



Inoculation Methods. — The guinea-pig is extremely sensi- 

 tive to tuberculosis by inoculation, and is the most suitable 

 animal for the purpose. The method of subcutaneous injection 

 as practised by Delepine ^ gives very reliable results. Two 

 guinea-pigs are each inoculated with the sediment from 40 

 c.c. of milk, the sediment being mixed with 2 c.c. of the 

 separated milk left in the tube. G-uinea-pigs of about 200 

 grms. weight are used, the injection being made subcutaneously, 

 with aseptic precautions, on the inner side of the leg, at 

 the level of the femoro-tibial articulation. If the inoculated 

 material contains tubercle bacilli, an infection of the glands 

 on the inoculated side takes place. The popliteal, superficial, 

 and deep inguinal, and usually the sublumbar glands on the 

 inoculated side are enlarged (see Fig. 11), and tubercle 

 bacilli can be demonstrated in films made from them. The 

 time at which this can be done varies with the number of 

 tubercle bacilli injected. According to Delepine, with milk 

 containing numerous tubercle bacilli definite evidence of 

 tuberculosis can be seen in animals killed after ten to fifteen 

 days ; when not sufficiently numerous to be detected micro- 

 scopically in the milk — i.e. a moderate number of bacilli — at 

 the end of fifteen days, and when very few bacilli are present 

 in the milk, it may be difficult to obtain any clear evidence of 

 infection before the end of the fourth or fifth week. DeMpine 

 lays stress upon the importance of keeping the inoculated 

 animals isolated and under favourable hygienic conditions. 

 For ordinary work a good plan is to inoculate two animals, 

 one being killed at the end of three weeks, and the other a 

 week or two later. 



While the pathological picture is practically conclusive of 

 tuberculosis, the complete proof should always be obtained by 

 finding tubercle bacilli in the enlarged glands and other tuber- 

 culous lesions. 



^ British Medical Journal, 1893, vol. ii. p. 664 ; Report of Medical Officer, 

 Local Government Board, 1908-9, p. 341. 



