IMMUNITY AND ANTITOXINS 263 



The jar containing the blood (which contains the anti- 

 toxin) is next placed in a dark, cool cellar, where it stands 

 for two or three days. During this time the blood naturally 

 coagulates, the corpuscles falling as a dense clot to the bot- 

 tom, and the faintly yellow serum rising to the top. The 

 serum, or liquor sanguinis, averages about 50 per cent, of 

 the total blood taken. Sometimes antiseptics are added 

 with a view to preservation. It is generally filtered before 

 bottling for therapeutic use, and sometimes examined 

 bacteriologically as a test of purity. 



4. The Use of Antitoxins. The antitoxins are now ready 

 for injection into the patient who has contracted diphtheria, 

 and in whose blood toxins are in the ascendency and under 

 which the individual may succumb. They are injected in 

 varying doses, as we have already pointed out. 1 The gen- 

 eral result is that mortality has been greatly lessened, 

 and that in fatal cases there has been a considerable length- 

 ening of the period of life. Moreover, the whole clinical 

 course of the disease has been greatly modified, and suffer- 

 ing lessened. 2 



1 The term unit is used as a standard measurement. This means the amount 

 of antitoxin which will just neutralise ten times the minimum fatal dose of the 

 toxin in a guinea-pig (250 grams toxin to kill on the fourth day). If I cc. of 

 the antitoxic serum is required for this, one unit is contained in I cc.; if o.oi 

 cc. is sufficient, then 100 units are contained in the cc. Not less than 1500 

 units should be administered for a dose, and repeated every twelve hours. 

 In severe cases two or three times this amount may be given. 



2 The value of antitoxin treatment in diphtheria is discussed in the Brit. 

 Med. Jour., 1899, pp. 197 and 268, by E. W. Goodall, M.D. 



