THE MANUFACTURE OF ANTISERA. 483 



cylinders. These cylinders are so constructed that accompanying steril- 

 ized needles and pistons may be conveniently applied and the antitoxin 

 injected hypodermatically directly from the containers. Each con- 

 tainer must bear a label indicating the number of antitoxin units enclosed 

 and the date of preparation. 



Finally, after the diphtheria antitoxin has been distributed in the 

 glass cylinders, sealed and packed ready for use, sample packages are 

 opened and examined for contamination, usually by two microbiologists. 

 The product is not approved until the independent results of these final 

 tests are compared, and it is assured that microbial contamination is 

 absent. 



All antitoxic sera should be kept away from the light and at a tempera- 

 ture of 10 to 15 whenever possible, as the presence of heat and light 

 causes gradual deterioration. Usually a time limit of from eighteen 

 months to two years is applied to diphtheria antitoxin and other antitoxic 

 sera. 



It has been demonstrated that the antitoxic content of serum is closely 

 associated with the globulins. Advantage has been taken of this fact 

 in some laboratories in reducing the volume of antitoxin, or concentrating 

 the product by precipitating out the globulins with ammonium sulphate, 

 redissolving the precipitate and dialyzing. 



TETANUS ANTITOXIN. The processes involved in the preparation of 

 antitetanic serum differ but little from those employed in the manufacture 

 of diphtheria antitoxin. The pure culture of B. tetani is inoculated into 

 large flasks of glucose bouillon, placed under anaerobic conditions and in- 

 cubated at body temperature. A convenient method of excluding 

 free oxygen, in the presence of which the tetanus organisms will not 

 multiply, consists in boiling the glucose bouillon before the inoculation, 

 to drive off the oxygen, then covering the liquid medium by a layer of 

 oil. These cultures are subjected to a temperature of 37 for several 

 weeks, after which they are examined microscopically, a preservative is 

 added and they are passed first through a Berkefeld filter, and finally 

 through a Pasteur filter. On account of the presence of spores and 

 the danger attending the contamination of any materials or biological 

 products with the tetanus bacillus, it is important that great care should 

 be exercised in the filtration and preparation of the tetanus toxin. There- 

 fore, the filtration process is best accomplished in an isolated room which 

 is used only for the preparation of tetanus toxin. 



