CULTURE MEDIA 97 



forced out into a sterile tube where it may be defibrinated 

 or mixed with citrate solution, or allowed to clot, as may be- 

 desired. 



Very large amounts of sterile blood are best obtained from 

 the jugular vein of the horse or the superficial abdominal veins 

 of the cow. The skin is shaved, washed and cauterized with 95 

 per cent carbolic acid. When this has dried the vein is punctured 

 with the needle, which is attached to a suitable glass receptacle 

 by means of rubber tubing. 



Collection of Sterile Ascitic Fluid. For this purpose a large 

 trochar and canula provided with a lateral outlet, and made so 

 that the trochar can be drawn back beyond this outlet without 

 being completely removed, is most convenient. The instrument 

 is oiled with liquid paraffin. A rubber tube about 40 cm. in 

 length is attached to the outlet and the whole is wrapped in a 

 cloth and sterilized in the autoclave. The site selected for punc- 

 ture should be cleansed and painted with tincture of iodine and 

 the skin may be frozen with ethyl chloride if desired. One man 

 inserts the trochar and canula, taking care not to contaminate 

 it after it is removed from the cover. Another manipulates the 

 attached rubber tube, carefully guarding it from contamination 

 and allowing the fluid to flow into sterilized flasks of 1000 c.c. 

 capacity which are handled by an assistant. The mouth of each 

 flask should^be flamed after removing the cotton plug and again 

 before it is inserted after filling the flask. With proper technic 

 the ascitic fluid will as a rale be found bacteria-free. It should 

 be stored in a cool place, and is most conveniently handled by 

 means of large Pasteur bulb pipettes. 



In collecting hydrocele fluid or other fluids to be used for 

 culture media, similar aseptic technic should be employed. 



Sterilization of Contaminated Fluids. Any of the clear fluids 

 may be sterilized, when this is necessary, by filtration through the 

 Berkefeld filter. The filtrate will usually prove less valuable 

 as a medium than the corresponding unfiltered naturally sterile 

 material. 



