MALLEIN. 385 



shining, desquamation occurs, evidences of pus-forma- 

 tion are seen, and, indeed, the abscess (purulent orchitis) 

 often breaks through the skin. Tlie diagnostic sign is 

 the tumefaction of the testicles. 



Mallein. — The filtered products of growth of the 

 glanders bacillus in fluid media represent what is known 

 as mallein — a solution of compounds that bear to 

 glanders a relation analogous to that which tuberculin 

 bears to tuberculosis. It is used with considerable suc- 

 cess as a diagnostic aid in detecting the existence or 

 absence of deep-seated manifestations of the disease, the 

 glanderous anifnal reacting, manifested by elevations of 

 body-temperature greater than 1.5° C, to subcutaneous 

 injections of mallein in from four to ten hours, while an 

 animal not so affected gives no such reactions. 



Mallein is prepared from old glycerin-bouillon cult- 

 ures of the glanders bacillus by steaming them for 

 several hours in the sterilizer, after which they are 

 filtered through unglazed porcelain. 



By some it is said that the repeated injection of mallein 

 in small doses confers immunity from infection by 

 bacillus iiiaUci upon animals so treated ; an opinion that 

 is entirely in accord with the principles underlying the 

 artificial induction of immunity in general. 

 25 



