CHAPTER XL 



METHODS OF PURE CULTURE. 



82. Nutrient Solutions. 



IN 15 of the Introduction it was stated that Liebig's theory 

 regarded the disintegration of the albuminoids as the true active 

 agency in fermentation. PASTEUR (VII.), the active opponent of 

 this theory, interested himself in the preparation of artificial media 

 which, though free from albuminoids, began to ferment when 

 inoculated with a minute quantity of fermentative organisms (e. g. 

 a trace of yeast). The oldest of these, generally known as Pasteur's 

 fluid, consists of 



Grams. 



Water . 100.0 



Ammonium tartrate . . . . . i.o 



Cane-sugar 10.0 



Yeast-ash (corresponding to one grin, yeast) . 0.075 



and was intended preferably for the cultivation of the higher 

 fungi (yeast in particular). Its suitability for bacterial cultures 

 was examined by Cohn, who found that for this purpose the sugar 

 could be dispensed with. On the basis of researches into the 

 requirements of yeast as regards mineral matters, ADOLF MAYER (I.) 

 proposed to employ, in place of the yeast-ash, which is soluble 

 only with difficulty, an artificially prepared solution of the salts 

 of which this ash is known from experience to consist. Utilising 

 this report, COHN (I.) prepared a nutrient solution which he named 

 " normal bacterial liquid," and which was composed of 



Grams. 

 Water . . . 100.0 



Potassium acid phosphate (KH 2 P0 4 ) 

 Tribasic calcium phosphate (Ca 3 (P0 4 ) 2 ) 

 Crystallised magnesium sulphate 

 Ammonium tartrate . 



0-5 

 0.05 



i.o 



NAGELI (IV.), relying on the results of his researches (indicated 

 in Chap, ii.) on bodies suitable for the nutrition of the lower fungi, 

 prepared three "normal liquids for fission fungi," one of them 

 having the subjoined constitution : 



Grams. 



Water 100.0 



Di-potassium phosphate (K 2 HP0 4 ) 

 Crystallised magnesium sulphate 

 Calcium chloride 

 Ammonium tartrate . 



O.I 

 0.02 

 0.01 

 1. 00 



