316 GLANDEES 



Serum Reactions. — kShortly after the discovery of agglutination in 

 typhoid fever, McFadyean found that the serum of glandered horses 

 possessed the power of agglutinating glanders bacilli. His later observa- 

 tions show that in the great majority of cases of glanders a 1 : 50 

 dilution of the scrum 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 found 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 obtained a distinct, 

 sedimenting reaction with a serum which did not agglutinate at all 

 distinctly in the ordinary method. Within recent times the sedimenta- 

 tion test by the ordinary method (p. 117) has been most generally used. 

 The general result seems to be that distinct sedimentation within thirty- 

 six hours with a serum dilution of 1 : 1000 may be taken as a positive 

 result, indicating the presence of glanders ; whilst reactions with dilutions 

 between this and 1 : 500 are highly suspicious but not conclusive. The 

 deviation of complement test (p. 127) is also applicable in the case of 

 glanders, and this has given valuable results in the hands of various 

 observers. Precipitin reactions may also be obtained on the addition of 

 mallein or an extract of the glanders bacillus to the serum of a glandered 

 animal. These reactions, which of course depend on the presence of anti- 

 substance in the blood in glanders, form important auxiliaries to the 

 method of diagnosis by means of mallein. 



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

 glanders bacillus grown for a suitable length of time, and, like tuber- 

 culin, is really a mixture comprising (1) 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. 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 1 c.c. is usually the dose for a 

 horse (McFadyean). Foth has prepared a dry form of mallein by throw- 

 ing the filtrate of a broth culture, evaporated to one-tenth of its bulk, 

 into twenty-five or thirty times its volume of alcohol. A white pre- 

 cipitate 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 McFadyean at the 

 sixth, tenth, fourteenth, and eighteenth hours 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 tender 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 



