APPENDIX. 



403 



stand for about twenty minutes at the temperature of the body, in order 

 to allow the fat to come to the surface, after which it is allowed to cool, 

 and the layer of cream is carefully removed. To the resulting slightly 

 opalescent fluid, i per cent, of albumen peptone is added, and the whole is 

 neutralized, boiled, filtered, and sterilized and used as nutrient gelatine. 

 This material, like agar-agar (which was first used by Frau Hesse), was 

 introduced into bacteriological work by a lady, Madame Raskina. 



Agar- Agar Peptone Meat Jelly. 



In place of 10 per cent, gelatine, we may use 1.5 per cent, of agar- 

 agar. This is prepared in much the same manner as the gelatine jelly, 



Photographs. Growths on oblique Agar-Agar surface of— 



1. White Torula. 



2. Yellow Torula. 



3. Aspergillus Albus. 



4. Scheuerlein's Cancer bacillus. 

 Numbered from left to right. 



except that it requires a more prolonged boiling before it can be properly 

 filtered. It is prepared in the following manner : — Cut into pieces, about 

 half an inch long, 15 grammes of agar-agar, place in a porcelain basin, and 

 soak in a strong solution of common salt for twenty-four hours, pick out 

 the coarse particles of dirt and wash thoroughly, then drain off the water ; to 

 the washed agar-agar add one of the following solutions : (i) Water, 1,000 

 grammes; beef, i pound ; peptone, 10 grammes; common salt, 5 grammes; 

 or (2) water, 1,000 grammes; Liebig's extract of beef, 5 grammes; albumen 

 peptone, 30 grammes ; common salt, 5 grammes. 



In (i) the beef is first extracted, as in the preparation of gelatine. The 



