252 ANTITOXINS 



Preparation of Antivenin. According to Calmette, horses may be 

 immunized by giving them weekly subcutaneous injections of gradually 

 increasing doses of cobra venom, heated to 70 C., for an hour, which 

 precipitates the irritant toxins without injuring the neurotoxin. The 

 initial dose is usually 0.01 gram, gradually increased until, by the end of 

 four months, 4 grams may be given at a single dose. The serum is then 

 tested by mixing increasing doses with the minimal lethal dose for a 

 young rabbit, and injecting the mixtures intravenously into a series of 

 rabbits. 



Since the neurotoxin may prove dangerous in any case of snake-bite, 

 antivenin may be given to advantage, although the local pain and ne- 

 crosis are not relieved by the serum. 



PRODUCTION OF POLLEN ANTITOXIN 



The pollen of certain plants is markedly toxic for susceptible in- 

 dividuals. In America the pollen of the golden-rod and of rag weed 

 frequently produce a syndrome of distressing symptoms known as 

 " autumnal catarrh." The onset and character of the symptoms of 

 pollen intoxication are strongly suggestive of an anaphylactic reaction. 

 Dunbar has studied pollen toxins quite extensively, and considers them 

 the etiologic factor in the production of hay-fever. 



Pollen antitoxin has been prepared by immunizing susceptible horses, 

 the toxin being isolated by mixing the ground pollen with 5 per cent, 

 sodium chlorid solution and 0.5 per cent, phenol at 37 C. for ten hours. 

 In the form of a proteid, it is then precipitated by adding eight to ten 

 volumes of 96 per cent, alcohol, dissolving the resultant white precipi- 

 tate in physiologic salt solution (Citron). 



THE MEASURE OF ANTITOXINS 



Antitoxin Unit. A unit is the definite measure of antitoxin in any 

 serum or solution that will neutralize a certain amount of toxin. As pre- 

 viously stated, the United States Government has established a definite 

 unit for the standardization of diphtheria and tetanus antitoxins, and 

 frequently examines the serums made by various licensed manufacturers. 

 Officers of the Public Health and Marine-Hospital Service purchase 

 from reliable pharmacists several grades of antitoxins made by each 

 manufacturer, which are then sent to the Hygienic Laboratory at Wash- 

 ington, where they are tested for potency, freedom from contamination 

 by bacteria, chemical poisons, especially tetanus toxin, and for excessive 



