BY C. J. POUND, F.R.M.H, 41 



THE METHOD OF PEEPARING TUBERCULIN IN THE. 

 STOCK INSTITUTE. 



Tuberculin is a sterilised, filtered, glycerine extract of pure 

 cultivations of the tubercle bacillus. That which is prepared in 

 England, France and Germany, is made from cultures of the 

 bacillus growing in peptonised beef broth, containing from G to 

 8 per cent of pure glycerine, as per samples exhibited. When I 

 first commenced in an experimental way preparing Tuberculin 

 in Brisbane, I adopted the same kind of nutrient media ; but in 

 consequence of the various lots of beef from which bouillon was 

 prepared, varying so much in quality, more particularly the 

 necessary salts of serum, which very materially interfered with 

 the standardising of the resulting tuberculin, I endeavoured 

 and succeeded in preparing a special form of nutrient media, 

 made up of pure chemicals, the whole being analogous in com- 

 position to the very best quality beef. 



Pure Peptone, an important and expensive item in the old 

 nutrient media is disregarded in the new fornuila, thereby con- 

 siderably reducing the expense of turning out a first-class. 

 article. 



The most important point is, that whenever we wish to pre- 

 pare fresh batches of tuberculin, we always have the satisfac- 

 tion of knowing exactly to a day when to filter our culture, provid- 

 ing of course the regulators attached to the Incubators have main- 

 tained an even temperature throughout the period required for 

 obtaining the desired amount of growth of the tubercle bacillus. 



The following is the formula of the nutrient media used in 

 the Stock Institute : — 



It will be noticed that there is no alburnum material present,, 

 while the nitrogenous element is supplied in the Asparagin. 



