48 



SOLID MEDIA 



serum froths considerably as it comes through the bougie. If filtration be decided 

 upon, a Berkefeld bougie through which the serum passes much more readily than 

 through the finer Chamberland F type should be used. The technique is described 

 at pp. 18 et seq. 



To facilitate the filtration of serum Miquel has devised an apparatus which works 

 at 40 C. The serum is poured into a cylindrical vessel containing a filtering bougie. 

 The cylinder with its contained bougie is placed in a double-walled vessel heated below 

 by a gas burner on which a regulator is placed. The bougie is connected by means 

 of india-rubber tubing to a conical flask with a tubulure attached to a water pump. 

 Before use the flask is sterilized in the hot air sterilizer and the bougie and rubber con- 

 nexions in the autoclave. The side tube of the flask should be plugged with wool. 



2. From a living animal. 



[A. Method recommended. When a living animal horse or bovine is 

 available, the technique will be as follows. 



[1. Take three or four large (2-3-litre) sterile Jena flasks. 



[2. Prepare a trocar Sivori's pattern (fig. 38, p. 49) is very suitable thus: 

 to the side tube attach a fairly long piece of india-rubber tubing, and to the 

 other end of the latter connect a piece of straight glass tubing long enough 

 to reach from the mouth to the bottom of the flask. Boil the apparatus 

 for an hour. 



[3. Take the trocar out of the water with a pair of sterile forceps, pass it 

 between the neck and the plug of one of the sterile flasks, and then wrap 

 the plug well round it. Pass the glass tube well down into the flask in the 

 same way. 



[4. Cleanse the skin of the neck of the animal, and pass the trocar into 

 the jugular vein as described at p. 49. 



[5. When the flask is about two-thirds filled, pinch the rubber tubing, get 

 an assistant to withdraw the glass tubing and pass it as in (3) into a second 

 flask. Release the pressure on the tubing, and fill the second, and in the 

 same way the third and fourth flasks. Care must be taken when withdrawing 

 the trocar in the first instance, and the glass tube later, that the wool plug 

 is so arranged that no air channel is left. 



[6. Take the flasks of blood to the laboratory and stand them vertically. 

 If any of the plugs be soiled with blood or do not fit well replace them 

 with sterile wool (see A. 2 p. 45). 



[7. When the clot has formed and the serum separated, proceed as in A p. 45. 



[8. The serum should be sterile, but as a precautionary measure a little 

 chloroform may be added to it or it may be heated to 55-60 C. for an 

 hour.] 



B. Roux and Nocard's method. Recommended. This method has the 

 advantage of furnishing a much clearer serum and a medium more favourable 



FIG. 37. Nocard's trocar. 



for growth than Koch's, and should therefore be adopted in preference to the 

 latter whenever possible. 



Instruments required. 1. A Nocard's trocar (fig. 37) on to the cannula of 



