THE TRANSMISSION OF RHUS POISON FROM PLANT 
TO PERSON! 
James B. McNair 
(Received for publication January 3, 1921) 
The progress of our knowledge of the transmission of Rhus poison from 
plant to person reflects, in a general way, the development of our under- 
standing of plants and plant products. This is shown prominently in 
tracing the history of experiments in regard to the volatility and chemical 
nature of the poison. In this connection it may be well to consider, besides 
the dermatitant from Rhus diver siloha T. & G., the similar irritant substances 
from R. Toxicodendron L. and from its other sub-species R. radicans L. 
The earHest explanation of Rhus poisoning attempted was that the plant 
gives off an invisible colorless vapor, or emanation, which, when breathed 
or permitted to touch the skin, causes dermatitis. The North American 
Indian and negro shared in this belief (Thompson, 44). 
Some early writers associated Rhus poisoning with the fabulous stories 
told of the effects of the deadly upas tree (Ipo toxicaria Pers., Antiaris 
toxicaris Lesch.) of Java (Bennett, 4).^ 
The theory that the poison is non-volatile has also had its adherents. 
^ The substance of this paper was presented before the Graduate Botanical Club of 
the University of Pennsylvania, May 6, 1918. 
2 More light on the early physical and chemical nature of the principal irritant poison 
of this plant may be obtained through a study of the writings of Monti, Hunold, Gled- 
itisch, Achard, Willemet, Pornai, and Kriiger, All of these investigators considered the 
poison volatile. That this conclusion should be drawn at that time is not so remarkable if 
we consider that the gaseous exchange in plants was not understood at that time. Although 
Priestly (39) found in 1772 that plants give off oxygen, subsequent repetition of his ex- 
periment did not always give the same result. Ingenhousz (20) showed that the air was 
purified by plants in sunlight. He concluded, however, that the atmosphere is made in- 
jurious to animals by emanations from all plants in the shade and at night. Not only were 
all plants supposed to give off volatile poisons in the shade or at night, but Conradi, Acker- 
man, and Krauss believed the chief cause of various infectious diseases to be gaseous. As 
a result we have to this day the word malaria. 
Achard, F. K. Nouv. Mem. de I'Acad. Royal de Sciences et Belles Lettres i: 48. 1786. 
Achard, F. K. Nachricht von Versuchen die iiber den Giftbaum {Rhus Toxicodendron 
Linn.) angestellt worden, um seine Bestandtheile zu kennen, und die Art und Weise, 
wie sein Gift auf verschiedene Thiere wirkt, zu bestimmen. Chemische Annalen von 
Lorenz Crell 1 : 387-395, 494-503. 1787. 
AcKERMANN, J. F. Von der Natur des ansteckenden Typhus; dem Wessn des Ansteck- 
ungsstoffs, der Art sich gegen denselben zu sichern, und der Methode die Krankheit 
zu heilen. Heidelberg, 1814. 
Conradi, — . Grundriss der Pathologic und Therapie i : 288. 
Gleditisch, J. G. Nouvelles experiences concernant les dangereux effets que les ex- 
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