MODES OF CULTIVATION 53 



obtained, which is slightly cooled and introduced into a 

 cork-borer so that no air-spaces remain. The pap is then 

 pushed out with a rammer and divided with a platinum 

 wire into separate discs, which are placed in glass boxes, 

 moistened with a few drops of milk, and sterilised, 

 and then serve as a nutrient medium on which the most 

 various micro-organisms grow in a characteristic manner, 

 particularly those which form pigments. 



The milk rice was modified by Eisenberg in the following 

 way: — 100 grm. rice powder, 70 grm. bouillon, and 210 

 grm. milk are rubbed up and introduced into glass boxes and 

 the mass heated on the water-bath until it solidifies. The 

 boxes having been closed and heated on three days in suc- 

 cession in the steam steriliser, a medium of the colour of 

 cafe au lait is obtained, on the smooth surface of which 

 the micro-organisms can be inoculated. 



Bread pap is prepared in the following manner : — Bread 

 is dried until it is fairly free from water, and is then crumbled 

 to powder and spread over the bottom of a flask so as to 

 cover it. By adding water a pap is formed which after 

 boiling yields without being neutralised an excellent medium 

 for the cultivation oimoulds, the Aspergillus niger developing 

 particularly well upon it. After neutralisation with sodium 

 carbonate the pap forms a nutrient medium for different 

 bacteria when it has been several times sterilised in the 

 steam apparatus. 



Wafers, especially the thicker ones, are, according to 

 Schill, to be chosen for ekromogenic bacteria. They are 

 moistened with bouillon, laid in glass boxes, and sterilised. 



Modes of Cultivation 



Slide cultures. — Microscopic slides covered with a layer 

 of gelatine have repeatedly been used to catch the micro- 



