222 WARFIELD T. LONGCOPE AND GEORGE M. MACKENZIE 



culation or tissues of the normal human being and the problem has pre- 

 sented many of the features and opportunities that occur with any 

 experimental investigation. It has been possible, therefore, to deal with 

 factors some of which are known and part of which can be controlled. 

 Even under these circumstances great obscurity still involves the under- 

 lying processes of the disease and it is no wonder, therefore, that the still 

 more complicated and difficult subject of hypersensitiveness or idiosyn- 

 crasy in which factors cannot be controlled should, in spite of much investi- 

 gation and study, present considerable mystery. 



It has been known for many years that certain individuals respond in 

 an abnormal manner to substances that are quite harmless to the ordinary 

 person. This peculiar idiosyncrasy may be manifest after the inhalation, 

 ingestion, or the skin contact with the substance in question. Such idiosyn- 

 crasy or forms of hypersensitiveness have been shown to occur in a cer- 

 tain proportion of individuals suffering from a variety of diseased con- 

 ditions such as hay fever, asthma, acute gastro-intestinal disturbances, par- 

 ticularly in children, and such affections of the skin as urticaria, eczema 

 and angioneurotic edema. It has further been demonstrated that the in- 

 halation, the ingestion, or the skin contact with one of several proteins or 

 even of substances that are non-antigenic in nature, may precipitate an 

 attack of the disease from which the patient may be a chronic sufferer. 

 Thus inhalation of ragweed pollen may precipitate an attack of hay fever, 

 or the inhalation of the epidermal dust of horses, dogs, and cats or of 

 fowls, may produce severe attacks of asthma in one hypersensitive to any 

 one of these proteins ; while the taking of an egg or of cow's milk, of cer- 

 tain fruits or vegetables, of quinin or the salicylates, may always call 

 forth in a given individual an attack of urticaria, asthma, or of violent 

 nausea and vomiting. And finally, the cutaneous contact with the pollen 

 of ragweed or the juice of a nasturtium or the leaves and pollen of prim- 

 roses may constantly give rise to urticaria or dermatitis in one who has an 

 idiosyncrasy for these substances. 



A comparison of the condition which exists in those individuals who 

 present such idiosyncrasies with that brought about by artificial sensitiza- 

 tion of the guinea-pig or rabbit, or with the hypersusceptibility or allergy 

 developing in the human being after the injection of foreign proteins such 

 as horse serum, discloses on the one hand important analogies and on the 

 other brings out differences so that at the present time it seems desirable to 

 consider this state of hypersensitiveness as a condition requiring study for 

 its own sake and not because of the similarities which it presents to ex- 

 perimental anaphylaxis. 



The similarities indeed depend largely upon the train of symptoms 

 caused by the intoxication following the contact with the specific substance 

 to which the person is idiosyncratic and these symptoms may vary from a 

 mild rhinitis or localized urticaria to a violent condition of shock, with 



