386 TETANUS 



of such a serum subsequent to infection, if symptoms, have 

 begun to appear, 1000 times this dose would be necessary ; a 

 few hours later 10,000 times, and so on. 



As the result of his experiments, Behring aimed at obtaining 

 a curative effect in the natural disease occurring in man. For 

 this purpose, as for his later laboratory experiments, he obtained 

 serum by the immunisation of such large animals as the horse, 

 the sheep, and the goat, by the injection of toxin accompanied 

 at first with the injection of iodine terchloride. It was found 

 that the greater the degree of the natural susceptibility of an 

 animal to tetanus, the easier was it to obtain a serum of a high 

 antitetanic potency. The horse was, therefore, the most 

 suitable animal. If now we take for granted that the relative 

 susceptibility of man and the mouse towards tetanus are nearly 

 equal, a man weighing 100 kilogrm. would require *1 grm. of 

 the serum mentioned above to protect him from inoculation 

 with the minimum lethal dose of bacilli or toxin. If symptoms 

 had begun to appear, 100 c.c. at once would be necessary, and 

 as the injection of such a quantity might be inconvenient, 

 Behring recommended that for man a more powerful serum 

 should be obtained, viz., a serum of which one gramme would 

 protect 100,000,000 grammes weight of mice. 1 The potency is 

 maintained for several months if precautions are taken to 

 avoid putrefaction, exposure to bright light, etc. To this end 

 5 per cent carbolic acid is usually added, and the serum is 

 kept in the dark. In a case of tetanus in man, 100 c.c. of 

 such a serum should be injected within twenty-four hours in 

 five doses, each at a different part of the body, and this 

 followed up by further injections if no improvement takes 

 place. Intravenous injection of the antitoxin has also been 

 practised, and, in cases which we have seen treated in this way, 

 has seemed to give better results than those obtained by the 

 subcutaneous method. The serum is warmed to the body 

 temperature and slowly introduced into a vein in the arm, the 

 pulse and respiration being carefully watched during the 

 proceeding. Ten to twenty c.c. can be injected every few hours, 

 and in all 100 c.c. should be given in as short a time as possible. 

 Henderson Smith has shown that when antitoxins to toxins of 

 the tetanus group are injected intravenously a high concentration 

 in the body fluid is maintained for some time and the op- 

 portunity for neutralisation of toxin is thus great. He suggests 



1 The antitetanic serum sent out by the Pasteur Institute in Paris has a 

 strength of 1 : 1,000,000,000. Of this it is recommended that 50 to 100 c.c. 

 should be injected in one or two doses. 



