PEPPER TREE AS A CAUSE OF HAY FEVER. 193 



viz., lucerne, sunflower. Cosmos, sweet pea, Gypsophila, Acacia, 

 scented Verbena, Hunnemannia ; smell of carrots and raw potatoes ; 

 other odours, for examjile, naphthaline; changes in temperature; 

 other changes in the weather; dust, smoke, stomach derangement, 

 and bacteria. Except in the case of grass pollen, I have rarely 

 found more than a single person suffering from any one of these 

 presumed causes, so that their importance, even collectively, 

 is small. 



XVII. Dr. Asiie's Eesults. 



Dr. E. Oliver Ashe, of Kimberley, tested the susceptibility 

 of some Kimberley hay fever patients by scarification and rubbing 

 in of pollen. Six individuals, not subject to hay fever, acted as 

 controls, and none of them gave any reaction. Of ten who were 

 subject to hay fever, six reacted to pepper tree pollen, and four 

 did not. Of these four, one stated that she attributed her trouble 

 to sunflowers, and testing similarly with sunflower pollen gave a 

 violent reaction. The pollen to which the other three were sensi- 

 tive was not determined. Dr. Ashe also arranged for experiments 

 to be made in the De Beers Laboratory to test whether pepper 

 tree pollen is wind-borne. Pepper tree pollen was found on the 

 plates, but they were all exposed very near to pepper trees, the 

 greatest distance from the nearest pepper tree being 50 feet. The 

 report of Mr. J. C. Moi'an, who carried out the experiments, con- 

 cludes : " . . . . when one considers the large number of 

 pepper trees in Kimberley it follows as a reasonable supposition 

 that there must be a considerable amount of pepper tree pollen in 

 the air on those hot windy days in early summer when the pepper 

 trees are in full bloom." I am indebted to Dr. Ashe for these 

 results, which were communicated by letter. 



It will be noticed that in Dr. Ashe's experiments, only 60 

 per cent, of the sufferers reacted to pepper tree pollen, whereas 

 in the Bloemfontein scarification tests (Potts, 1921) all the hay 

 fever patients reacted. I was investigating only what is here 

 known as epidemic hay fever, and so tried to confine myself to 

 typical epidemic patients. It is usually possible to recognise 

 such sufferers by a few questions. 



XVIII. Acknowledgments. 



Valuable assistance in carrying out this investigation has 

 been given by many persons both in Bloemfontein and elsewhere. 

 Acknowledgment of some has already been made in the two 

 previous articles, and in the text of the present communication. 

 ]\luch of the detailed work, especially that of examining the pollen 

 plates, was done by Miss J. Eaubenheimer (now Mrs. S. H. 

 Pellissier) and Miss Helen Bergstedt, successive Demonstrators 

 in Botany. The task of searching for pollen amongst the Bloem- 

 fontein dust was especially arduous, and demanded close and 

 constant application. Miss Bergstedt also took charge of the 

 work in 1921 during my absence on furlough. 



