203 

 growing the tubes in the incubator for many days. 



(SCHAFFER.) 



LABORATORY WORK. The student should test, by the 

 methods given, the disinfecting action of mercuric chloride 

 (1-1000), carbolic acid (5 per cent), hydrochloric acid 

 (0.4 per cent.). Anthrax bacillus, anthrax spores, staphy- 

 lococcus pyogenes aureus, cholera, typhoid fever and 

 dipththeria bacilli may be used, suspended in distilled 

 water, bouillon and blood-serum. 



The blood-serum required in this work may be readily 

 prepared as follows: The flowing blood from an ox or 

 calf is received into a large sterilized Erlenmeyer flask 

 and when firmly clotted is carried to the laboratory and 

 placed in the ice-chest. After 24 48 hours the clear yel- 

 low serum separates out. A portion of this may be placed 

 in a beaker, diluted with 510 parts of distilled water, 

 then filled into tubes and sterilized as in the case of or- 

 dinary bouillon. The dilution with water prevents coagu- 

 lation of the blood-serum. Another portion of the blood- 

 serum may be filled direct in tubes which are then placed 

 in an inclined position in an air-bath and the temperature 

 slowly raised to about 80 C. which is maintained for 

 about one hour. The serum coagulates in the inclined 

 position. On the following day the tubes should be steri- 

 lized in the steam sterilizer for ^ 1 hour. 



To obtain undiluted fluid blood-serum the blood is re- 

 ceived directly from the artery or vein into sterilized jars 

 or flasks which are protected against contamination from 

 the air. As soon as the serum separates it is transferred 

 by means of a sterilized pipette to the sterilized tubes. 

 When this is properly done no organisms are introduced 

 into the serum and hence it requires no subsequent steri- 

 lization. 



>i, 



OF THE 



UNIVERSITY 

 of 



