MALLEIN: ITS PREPARATION AND USE. 283 



with vaseline containing the bacilli might produce the disease, 

 the bacilli in this case entering along the hair follicles. 



Agglutination of Glanders Bacilli. — Shortly after the discovery of agglu- 

 tination in typhoid fever, M'Fadyean showed that the serum of glandered 

 horses possessed the power of agglutinating glanders bacilli. His later 

 observations show that in the great majority of cases of glanders a i in 50 

 dilution of the serum produces marked agglutination in a few minutes, whilst 

 in the great majority of non-glandered animals no effect is produced under 

 these conditions. The test performed in the ordinary way is, however, not 

 absolutely reliable, as exceptions occasionally occur in both directions, i.e. 

 negative results by glandered animals and positive results by non-glandered 

 animals. He finds that a more delicate and reliable method is to grow the 

 bacillus in bouillon containing a small proportion of the serum to be tested. 

 In this way he has obtained a distinct sedimenting reaction with a serum 

 which did not agglutinate at all distinctly in the ordinary method. Further 

 observations are still required to determine the precise value of the test. 



Mallein and its Preparation. — Mallein is obtained from cultures of the 

 glanders bacillus grown for a suitable length of time, and, like tuberculin, is 

 really a mixture comprising (i) substances in the bodies of the bacilli and (2) 

 their soluble products, not destroyed by heat, along with substances derived 

 from the medium of growth. It was at first obtained from cultures on solid 

 media by extracting with glycerin or water, but is now usually prepared from 

 cultures in glycerin bouillon. Such a culture, after being allowed to grow for 

 three or four weeks, is sterilised by heat either in the autoclave at 115° C. or 

 by steaming at 100° C. on successive days. It is then filtered through a 

 Chamberland filter. The filtrate constitutes fluid mallein. Usually a little 

 carbolic acid (.5 per cent) is added to prevent it from decomposing. Of such 

 mallein i c.c. is usually the dose for a horse (M'Fadyean). Foth has pre- 

 pared a dry form of mallein by throwing the filtrate of a broth culture, evapo- 

 rated to one-tenth of its bulk, into twenty-five or thirty times its volume of 

 alcohol. A white precipitate is formed, which is dried over calcium chloride 

 and then under an air-pump. A dose of this dry mallein is .05 to .07 grm. 



The Use of Mallein as a Means of Diagnosis. — In using mallein for the 

 diagnosis of glanders, the temperature of the animal ought to be observed for 

 some hours beforehand, and, after subcutaneous injection of a suitable dose, 

 it is taken at definite intervals, — according to M'Fadyean at the sixth, tenth, 

 fourteenth, and eighteenth hoilrs afterwards, and on the next day. Here both 

 the local reaction and the temperature are of importance. In a glandered 

 animal, at the site of inoculation there is a somewhat painful local swelling 

 which reaches a diameter of five inches at least, the maximum size not being 

 attained until twenty-four hours afterwards. The temperature rises 1.5° to 

 2° C, or more, the maximum generally occurring in from eight to sixteen 

 hours. If the temperature never rises as much as 1.5°, the reaction is con- 

 sidered doubtful. In the negative reaction given by an animal free from 

 glanders, the rise of temperature does not usually exceed 1°, the local swelling 

 reaches the diameter of three inches at most, and has much diminished at the 

 end of twenty-four hours. In the case of dry mallein, local reaction is less 



