376 TUBERCULOSIS 



are used to determine the degree of dilution necessary, so that 

 20 c.c. of the vaccine should contain 4 milligrammes of solid 

 substance. The doses given were between 0*25 and 0*5 c.c. They 

 were checked by opsonic control twice weekly, and were in 

 general given once a week or fortnight. Bassett-Smith does not 

 approve of the method in acute cases, but his chronic ones 

 seemed decidedly benefited. 



The prophylactic use of the vaccine has not been tried on a 

 scale sufficiently large to enable any very definite inferences to 

 be drawn therefrom. The doses may be 200 to 400 million 

 cocci, and in general two are given, the results being judged by 

 their effect on the agglutination reaction. As noted above, some 

 bad local results have been noticed, and there is in all cases a 

 good deal of fever, malaise, and inflammation at the site of injection 

 and corresponding lymph glands. 



Tubercle. 



The actual toxin and mode of action of the tubercle bacillus 

 remain unknown. The most interesting substance which has 

 been derived from cultures of the organism is tuberculin, which 

 has been discussed previously. That it is not the true toxin 

 appears from the fact that animals immunized to it are still 

 susceptible to the tubercle bacillus, and a serum can be prepared 

 which appears to be an antitoxin for tuberculin, but it has no 

 curative or preventive effects in tubercle. The fatty substances 

 which confer on the bacillus its peculiar staining properties are 

 not devoid of toxicity. They cause chronic inflammatory and 

 caseous changes in the tissues, and may perhaps play a larger 

 role in the evolution of the lesion than is generally thought. And 

 it must be pointed out that tuberculosis may be an afebrile 

 disease throughout. The temperature of phthisis is mainly due to 

 other organisms, notably to the pyogenic organisms which form 

 such frequent secondary contaminations of the vomicae. The 

 chief pure tuberculous affection in which fever is a marked and 

 constant symptom is tubercle of the meninges, and here the local 

 processes are in close proximity to the cerebral cortex. In general 

 tuberculosis there is usually fever, but there is also usually a 

 focus exposed to secondary infections, or a broncho-pneumonia in 

 which other organisms play a part. The main toxic effect which 

 we recognize as being due to the tubercle bacillus is exerted on 

 the surrounding tissues, and there is no disease which is more 



