Ramon and his associates in their many studies on active immunization with tetanus toxoid (not alum precipitated) have demonstrated that further stimulation with toxoid results in the rapid formation of tetanus antitoxin. On this continent Sneath and Kerslake,1 Jones and Moss,2 Gold,3 Hayden and Hall4 and Hall,5 among others, have corroborated the results of the French workers. Their studies deal largely with nonallergic adults.
In my previous study6 on the appearance of tetanus antitoxin in the blood serum following two injections of 0.5 cc. each of combined alumprecipitated diphtheria and tetanus toxoids, special reference was made to the influence of age and the interval between injections. It was also shown that 94.6 per cent of a group of 186 allergic children attained a protective level of tetanus antitoxin, the critical level being placed at 0.01 American unit of antitoxin per cubic centimeter of blood.