In a previous paper,1 it was shown that skin sensitivity to scarlatinal streptococcus filtrate toxin was present at birth in only a small number of infants, and that in most infants up to 3 months of age, the skin did not react to a considerable amount of the toxin. This lack of skin sensitivity was not entirely due to the presence of antitoxin, since many such infants without a demonstrable amount of antitoxin in the blood had negative skin reactions between one and three months after birth. Those without antitoxin at birth, however, developed some skin sensitivity to the toxin within three months in a larger percentage than those in whom antitoxin was demonstrable.
The present paper deals with a study of the skin sensitivity to toxin during later infancy and childhood. It was not possible to follow up the same infants tested at birth except in occasional instances,