PEPPER TREE AS A CAUSE OF HAY FEVER. 



165 



Signal Road and BJignaut Street aie in the Eaihvay area 

 of the town, wliere, too, pepper trees are numerous. The plates 

 were hung near residences where patients were suffering- from 

 the epidemic. 



Plates dated after Decemher 20 were examined direct : the 

 otliers after centrifuging. Table IX gives the meteorological ob- 

 servations covering tlie period during which plates were exposed. 



(c) Bloewfontein, November and Decemher, 1921, and General 

 Femarlxs on the three years' results. 



During the epidemic season of 1921 plates w.ere exposed at 

 Bloemfontein over a period of IB days between November 14 and 

 December 6. Particulars are given in Table X and weather 

 records for the same period in Table XI. The plates were ex- 

 posed in pairs, on one occasion in triplicate, on the balconj- of 

 the Eamblers' Club, some 28 feet above the ground. This site, 

 as has already been explained, is central and fairly typical of re- 

 gions of the town where p.epper trees are plentiful. The two 

 situations in which plates were regularly hung were respectively 

 40 and 16 paces from the nearest pepper tree. 



Dust and p.epper tree pollen wei'e found on all the slides, 

 and no other pollen, ignoring single grains, was found on any. 



Table X 



Exposure of Pollex Plates : Bloemfontein, November and 

 December, 1921. 



It will be noticed that at Bloemfontein during the epidemic 

 season of 1920 and 1921 pollen plates were exposed only in areas 

 where pepper trees are plentiful, but had pollen of any kind been 

 generally distributed through the air of the town it, too, should 

 have been caught on the pollen plates. The results agree gener- 

 ally with those of 1919 and emphasise th,e presence of dust and 

 pepper-tree pollen in the air of the town. It is remarkable that 

 during these two epidemic seasons, if varieties of pollen of which 

 only a single grain was found on a plate be again ignored, no 

 pollen other than that of the pepper tree was found on the 

 plates. During tliese two seasons nearly all the plates were ex- 

 posed at or in the vicinity of the Ramblers' Club, a centre at 

 which the monotony of the pollen content of the air has already 

 been commented oh in discussing the 1919 results. In fact, from 

 the point of view of pollen statistics, the air of Bloemfontein 

 generally would have been extraordinarily dull in these seasons 

 but for the pepper tree. 



