Note on Idiosyncrasies and Abnormalities in Human Beings.

Idiosyncrasies are the expression of abnormal mental or physical reaction towards "agents." An attempt is made to indicate the position of idiosyncrasies in a classified scheme of all abnormalities; but bodily idiosyncrasies due to an "allergic" or hypersensitive response to agents are mainly considered in the present paper. Migraine and mucous colic ("colitis mucosa") are discussed in connexion with Freeman's view of food idiosyncrasies, hay fever, asthma, urticaria, angioneurotic oedema, &c., as manifestations of an "immunological abnormality or defect."The hypothesis that idiosyncratic hypersensitiveness towards physical agents, such as light, heat, cold and mechanical trauma, may in reality be the expression of reaction towards a histamine-like body, or protein of some kind (virtually a "foreign protein") liberated in the tissues by the physical agent in question, is referred to, according to the works of W. W. Duke and Sir Thomas Lewis and his co-workers, and the writings of Sir Humphry Rolleston on the subject. A somewhat analogous explanation is suggested for the following conditions: an abnormally hypersensitive (eczema-like) reaction towards formalin lotions; epidermolysis bullosa; constitutional factitious urticaria in otherwise healthy individuals not suffering from ordinary urticaria; excessive liability to chilblains; so-called "erythrocyanosis" of the lower parts of the legs in girls and young women, and some cases of Raynaud's disease.The significance of eosinophilia in cases of dermatitis herpetiformis and pemphigus is also alluded to.