There are many points in which the manifestations of hypersensitiveness differ in infancy and in childhood from those encountered in adult life. It is our purpose to consider only those points which pertain to the acquisition and the loss of individual sensitivities.
There are certain generally accepted impressions which bear on this subject, which should be mentioned before studying detailed evidence more closely. In the first place, it is recognized that states of hypersensitiveness are much more frequently encountered in late infancy and early childhood than in adult life. This difference is admittedly largely due to the frequency of food idiosyncrasies at this age, which more than compensates for the very infrequent finding of hay-fever and asthma caused by hair or feathers. Furthermore, it is evident that the medical profession recognizes the transient character of these food idiosyncrasies, for they treat the finding by elimination only and assure the parents