HYPERSENSITIVENESS 569 



It was established as early as 1904 by Nestler that this form of 

 hypersensitiveness can be induced by the repeated application 

 of the exciting agent to the skin of a nonsensitive individual. He 

 rendered himself allergic to the juice of primrose leaves. Bloch 

 and Steiner-Wourlisch (1926) confirmed Nestler 's results. Straus 

 (1931) succeeded in sensitizing 48 babies to extracts of poison ivy 

 loaves. In all of these experiments local sensitizing applications 

 caused the entire skin of the individual to become sensitive. Anti- 

 bodies have not been demonstrated by passive transfer. In many 

 individuals a positive skin reaction is obtained only when the excit- 

 ing agent is kept in contact with the skin for a long period of time 

 such as occurs when the ''patch test" is used. The scratch and 

 intradermal tests are always negative except where surface contact 

 occurs in performing the test and the individual is quite sensitive. 

 In many cases of poison ivy, poison oak, pollen dermatitis, etc., an 

 increased tolerance corresponding to desensitization has been pro- 

 duced by the injection of a 1 per cent solution of the exciting agent 

 in sterile almond oil. Divergent results have been reported by 

 numerous investigators. For a more extensive discussion of the 

 subject the student is referred to the studies of Zisserman and 

 Birch (1939), Stratton (1940), and a review of the literature by 

 Goodman and Sulzberger (1940). References to the other papers 

 are given in the supplementary list at the end of this chapter. 



Substances Responsible for Contact Dermatitis. — Coca 

 (1931) lists a large number of substances that may cause contact 

 dermatitis. Among them he mentioned the leaf, stalk and root of 

 such plants as poison oak, poison ivy, poison sumac, primrose, 

 chrysanthemum, tomato, geranium, lily and a number of others; 

 many chemicaLs such a.s formalin, photogravure ink, hexamethylen- 

 amine, scharlaeh rot and various dyes, etc. ; among the miscel- 

 laneous materials that have been reported as causing contact 

 dermatitis he lists soaps, adhesive plaster, orange peel, cement, 

 furniture polish, feathers, cereals, lanolin and a number of others. 

 In addition to these there are on record numerous cases of contact 

 dermatitis in individuals handling plant pollens. It is interesting 

 to note that in pollen dermatitis the exciting agent is an oil, while 

 in pollen hay fever it is a water-soluble substance. While these 



