Chemical Preparations and Drugs. 95 



evening -primrose (Oenothera biennis), rape (Brassica Napus) and spinach (Spinacia 

 oleracea), as well as a number of composite, is efficacious with European hay-fever 

 patients. The American autumnal catarrh (fall fever) is caused by the pollen of 

 Ambrosia and Solidago species. American patients who only suffer from the spring 

 catarrh, but not from the autumnal one, are only affected by grass pollen, whereas a 

 third group of patients is sensitive towards the pollen of gramineas as well as towards 

 that of composite. Besides, also in Europe highly sensitive persons have been found, 

 who are irritated by either kind of pollen. Finally, Dunbar succeeded in proving that 

 privet pollen is the cause of the Chinese hay-fever and the pollen of an Eragrostis 

 species, widely spread in South Africa, of that of the South African hay-fever. 



According to Prausnitz and Liefmann, the pollen begins to increase in Hamburg 

 already towards the end of May, reaches its maximum about middle of June, in marked 

 coincidence with the intensity of hay-fever, and starts diminishing gradually in the 

 second half of July, so that at the end of July or early in August only stray pollen 

 are still found. With the aid of a special aeroscope, Liefmann was able to prove 

 that, in the centre of the large town, 308 pollen were contained in one cubic metre 

 of air on the 10 th July and that in the neighbourhood of a rye field one takes in 2 

 or 3 pollen with every breath. As 40 to 50, with highly sensitive patients only 2 to 

 4, suffice to cause hay-fever, the figures given show that the pollen contained in the 

 air are sufficient to cause the attacks. 



The poisonous action of the pollen is due to a toxical albumen, which may be 

 obtained from a pollen extract by precipitation with alcohol, or by dialysis. As per 

 Kammann's investigations, the rye pollen protein prepared in this way is a thermo- 

 stable poison, which remains unaltered on heating for one hour up to 60 or 70° 

 and only on being boiled loses three-fourths of its original efficacity. It is not attacked 

 by sulphuric acid, but potash lye, trypsin, and pepsin, combined with hydrochloric acid, 

 destroy it to a great extent. The introduction of one drop of a 1 : 20 000 down to 

 1:40000 solution of the poison, obtained by precipitation with alcohol, into one eye, 

 or the nose, of a hay-fever patient will cause the characteristic symptoms within a 

 few minutes, whereas normal people will remain completely unaffected. The sub- 

 cutaneous injection of the poison was followed by violent attacks of hay-fever, accord- 

 ing to Dunbar's observations. The method of preparing the poison has been further 

 improved of late by Kammann, who succeeded in preparing a solution of it, which 

 kept its efficacity unaltered for years and, even in a 300-millionfold dilution, brought 

 about the typical symptoms in highly sensitive hay-jever patients. 



The isolation of the rye pollen protein has enabled the physician to satisfy himself 

 at all times as to whether a patient suffers from European or American hay-fever, or 

 from some other illness (vasomotoric coryza, §c.). Instead of the pollen extract, not 

 always available, and which must always be freshly prepared, he may use the so- 

 called hay-fever diagnostic, which is quite harmless for otherwise healthy eyes and has 

 become indispensable for differential diagnosis. 



The improvement of the preparation of the pollen toxin proved useful also in that 

 animals can be immunized with Kammann's preparation to a much higher degree than 

 it was possible with the former protein. On treating them with subcutaneous or intra- 

 venous injections of pollen protein, certain bodies appear in the serum of these ani- 

 mals which are capable of neutralizing the poison. Already in his first publication, 

 Dunbar was able to report that such an antiserum altered a solution of pollen toxin 

 in vitro to such an extent as to make it absolutely ineffective towards hay-fever patients, 

 and that furthermore the irritation caused through pollen toxin could be removed 



