In the course of a study1 of skin sensitivity to scarlatinal streptococcus filtrate toxin in infants and younger children, it was noted that those in close contact with one another in an asylum showed striking differences from children in isolated homes. These differences, together with their relation to the presence of hemolytic streptococci in the pharynx, and to the presence of antitoxin in the blood, form the subject of this report. In addition, the variation in skin sensitivity which accompanies measles and possibly some other nonscarlatinal infections has been studied.
The skin tests were made as previously described,1 with 2, 20 and 50 standard skin test doses (STD) of a potent scarlatinal streptococcus filtrate that contained 100,000 STD per cubic centimeter. Antitoxin determinations were made by toxin neutralization tests. Pharyngeal cultures for hemolytic streptococci were made by rubbing a sterile swab, moistened with salt solution, on the