PRACTICAL APPLICATIONS 383 



The agglutination reaction has been recommended as a means of 

 diagnosis, but it is not always present at any stage of the disease, 

 and there are practical difficulties in the way of its determination. 

 It does not appear to have come into general use even in France, 

 where much attention has been paid to it. 



Treatment. The essays at a serum treatment have been many, 

 and no method has attained any appreciable degree of success. 

 Good results have been obtained, it is true, by several, especially 

 in the hands of their inventors, but recent work by Hort and 

 others has shown that normal horse serum has some value as a 

 curative agent. Maragliano's serum appears to be prepared by 

 injecting animals with various extracts of tubercle bacilli, and 

 is supposed to be both bactericidal and antitoxic. It is given 

 either alone or in conjunction with a vaccine. McFarland 

 prepared an antituberculin by immunizing donkeys for long 

 periods with tuberculin, and found that it annulled the effects of 

 tuberculin on tuberculous animals, but had no protective or 

 curative powers as tested on guinea-pigs. Clinical evidence 

 appeared to show that it was of some value. 



Marmorek's toxin is quite different from any of the others, 

 which are various extracts of tubercle bacilli, or of their soluble 

 products. It is prepared by cultivating young bacilli (prepared 

 in such a way that they form homogeneous emulsions) in a 

 medium containing leucotoxic serum, prepared by injecting calves 

 with guinea-pig leucocytes. It is supposed to be the actual 

 toxin which is developed in vivo. This substance (which is of 

 feeble toxicity) is used to immunize horses. Some good results 

 have been obtained, but perhaps we may attribute them to minute 

 amounts of tuberculin which may be formed in the cultures and 

 remain unabsorbed in the blood of the horse when it is bled. The 

 experience of most observers has not been favourable to its use. 



The other sera which have been introduced do not call for 

 further notice. 



The most hopeful method of combating tubercle other than 

 the all-important use of fresh air, good food, and careful regimen 

 consists in the use of a vaccine. There are many to choose from 

 old tuberculin, TR, BE, bovine tuberculin, oxytuberculin, 

 antiphthisin, etc.; but of these, Koch's preparations (old tuber- 

 culin, TR, and BE) are the only ones in general use, and appear 

 at least as good as any. 



TR (tuber culinum residmtm) is prepared by triturating living, dry, 



