190 



PEPPER TREE AS A CAUSE OF HAY FEVER. 



Chart (from Cox, 1922). 

 Mean Maximum Temperatures and Relative Humidity. 



— Reference — 



temperatures' — .— ^ ordi nates 

 represent decrees fahrenheit 



Relative Humidity— — — 



ORDINATES REPRESENT PEftCElfTACL 

 OF SATURATION 



the pepper tree on a circular or square block of any considerable 

 size in them would be very low. Such small scattered towns 

 should be considered, not as a whole in this connection, but 

 rather as groups of isolated houses with pepper trees around 

 them. 



There is evidence that the suffering of many Bloemfontein 

 patients Is largely due to a few pepper trees near to, and 

 especially on the windy side of their residences. The benefit 

 which some patients in Bloemfontein have derived from remov- 

 ing the pepper trees around their own erf, or from a change of 

 residence to a house near which there were fewer or no pepper 

 trees, also points to the same conclusion. This experience is in 

 agreement with that recorded by Dr. Scheppegrell (Scient. 

 Americ. Suppl. 1916), who found that hay fever caused by 

 weeds was mainly due to plants in the immediate vicinity of the 

 patient, and that the removal of these weeds gave great relief, 

 although there was still some pollen in the air from weeds at a 

 greater distance. 



