CHAPTER XL 



MKTHODS OF PURE CULTURE. 



82. Nutrient Solutions. 



< 15 of the I lit rod lift ion it w.is stated that Liebig's theory regarded the 



di.-hitrgration 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 



tVrnifht when inoculated with a minute quantity of fermentative organism- 



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



.f 



< Irani*. 



Wat.r 100.0 



Ammonium tartratr ....... I o 



Cane-sugar ......... 10.0 



(corresponding to on*- L- rin. vast) . . . 0.^75 



;u,d was intended preferably for the cultivation of the higher fungi (yeast in 

 particular). Its suitability for bacterial cultures \\MS examined by Cohn, who 

 found that for this purpose the sugar could be dispensed with. On the basis of 

 i relies 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 ditlicultv. 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 



Gnna 

 Wat^r . i oo.o 



Potassium acid phosphalf (I\ILP0 4 ) 



dc ralcinm phosphate (<';\ 

 Cr\-t;illis.-(l mairnrsiimi sulphate . 

 Ammonium tartr.-itr 



0-5 

 0.05 

 0.5 

 i.o 



N \;I;LI (I \'.). relying on the results of his researches (indicated in chapter ii.) 

 on hodii-s suitable for the nutrition of the lower fungi, prepared three " normal 

 ^ t'nr (i ion I'imiM,'' one of them having the subjoined constitution : 



Di-potamium pin.-p}i:it>- 1 K .,Hl'< Y 



iiim sur'phat.- 

 ("alciiini rlilori.l.- . 

 Ammonium tartrat- 



(Ir.iin-. 



IOO.O 

 O.I 

 O.O2 

 O.OI 

 1. 00 



hitherto described play a great part in earlier myco- 



logical literature, on which account their constitution is n>w given, though at 

 present they are but seldom 



< >n the other hand, a -vond nutrient solution given by Pasteur, viz , yeast- 

 water, is still frequently used. To prepare this solution, about 100 grins, of 

 thick brewer's barm (or 75 grins, of pn . -d yeast) are placed in a tin can with 



94 



