PEPPER TREE POLLEN AND HAY FEVER. 341 



had been eliminated. This extract, like that in saline, may have 

 failed entirely to extract the active toxic principle or may have' 

 done so in insufficient quantity, yet experience has shown that 

 in the case of many, or perhaps all toxic pollen tried, it has been 

 possible, after a few preliminary trials, to prepare the saline 

 extract in such a strength as to give a reliable reaction. 



To the fourth scarified area normal saline, or 0.5 per cent, 

 sodium carbonate was applied. This was done as a sort of control 

 to ensure that any reactions obtained were not due to the scari- 

 fication itself or to the solvents in which the pollen extracts were 

 dissolved. As, with the exception of patient No. 3, whose response 

 has been accounted for, only one of the fifteen patients gave any 

 reaction at all, and that a very mild one to this control inocu- 

 lation, the reactions obtained from the pollen itself and the extract 

 may be justly referred to the toxic principles in these materials. 



These simple experiments demonstrate conclusively the toxicity 

 of pepper tree pollen ; the question of its dispersal and the probable 

 part it plays in causing the epidemics under investigation will 

 be discussed in a subsequent article. 



Thanks for aiding in the investigation are due in the first 

 place to the patients who allowed themselves to be inoculated, 

 to Dr. S. M. de Kock, himself a sufferer, who performed the 

 inoculations, and who throughout the investigation has always been 

 most willing to render whatever assistance his time allows; to Dr. 

 W. Watkins-Pitchford, Director of the S.A. Institute for Medical 

 Research; and Dr. J. H. Harvey Pirie, for much friendly and 

 valuable advice; and to Miss Helen Bergstedt, B.Sc, Demonstrator 

 in Botany, for general assistance, especially in preparing the 

 pollen. 



R EFERENCES . 



1. Pfaff, Fr. (1897). Active Principles of Rhus toxicodendron and 



Rhus venenata. Jour. Fxper. Med. Vol. ii. p. 181. 



2. Potts, G. (1919). The Pepper Tree (Schinus molle) in its Relation 



to Epidemic Hay-Fever. Interim Report. S.A. Journal of 

 Science, Vol XV, p. 525-530. 



3. Smith, F. Philip (1920). Plant Dermatitis. Journal of Botany, 



May, 1920. 



