BLOOD SERUM MEDIA 



41 



sterilisation of the serum is unnecessary. To this end the mouth 



of the cylinder used for collecting the blood, instead of being 



plugged with wool, has an indiarubber bung inserted in it 



through which two bent 



glass tubes pass. The 



outer end of one of these 



is of convenient length, 



and, before sterilisation, a 



large cap of cotton wool 



is tied over it ; the other 



tube is plugged with a 



piece of cotton wool. In 



the slaughter - house the 



cap is removed and the 



tube is inserted into the 



blood-vessel as a cannula. 



The cylinder is thus easily 



filled. Another method is 



to conduct the blood to 



the cylinder by means 



of a sterilised cannula 



and indiarubber tube, the 



former being inserted in 



the blood-vessel. In every 



case the serum must be 



incubated before use, to 



make sure that it is 



sterile. 



Coagulated Blood 

 Serum. If fresh serum 

 be placed in sterile tubes 

 and be steamed in the 

 sloped position for an 

 hour, it coagulates, and 



FIG. 8. Blood serum inspissator. 



there is thus obtained a solid medium very useful for the growth 

 of the diphtheria bacillus for diagnostic purposes. 



Loffler's Blood Serum. This is the best medium for the 

 growth of tin- b. diphtheria?, and may be used for other organisms. 

 It has the following composition : Three parts of calf's or lamb's 

 blood serum are mixed with one part ordinary neutral peptone 

 bouillon nijulo from veal with 1 }>er cent, of grape sugar added 

 to it. Though this is the original formula, it can be made from 

 ox or -Invp scrum and beef bouillon without its qualities being 

 markedly impaired. Sterilise by method B (4) as above (p. 30). 



