PRINCIPALLY SOLANACEOUS AND COMPOSITOUS PLANTS 113 



be set aside. Foreign bodies may produce sneezing, but not the after 

 effects. E. Philip Smith suggests that there is an oily substance on the 

 outer wall (exine) of the pollen grains which cause hay fever. Experi- 

 menting with pollen of Hibiscus, he found upon shaking it up with cold 

 ether, that an oil could be obtained by allowing the ether to evaporate. 

 This oily residue applied to the skin raised a severe blister. If this idea, 

 that the poisonous principle of pollen is an irritant oil, a new light is thrown 

 upon the nature of the poisoning which resolves itself into a kind of 

 dermatitis, or irritation of the delicate, ciliated epithelium lining the 

 nasal cavities. 



Granted that the pollen of these plants is responsible for hay-fever, 

 the way of controlling the disease would be the extermination of the plants. 

 This might be accomplished by hand pulling, if every one would cooperate in 

 this laudable enterprise. Barring the entire destruction of these noxious 

 weeds, mowing just before they start to shed their pollen would be a 

 means of their final destruction, as this would prevent the formation of 

 seeds upon which the perpetuation of the species depends. Concerted 

 action should be taken to exterminate these useless and deleterious 

 ragweeds. 



Remedies. Recent work has been done along remedial lines by 

 securing a hay-fever vaccine to be used in the immunization of the suscep- 

 tible person. To secure this vaccine, the flowers of the various hay-fever 

 plants are collected when pollination has started. They are dried and the 

 pollen collected by means of fine sieves. The pollen is dried thoroughly 

 and preserved in a dry state until it is to be extracted. In the preparation 

 of the extract. 



1. The pollen is mixed with sufficient physiological saline solution 

 (0.85 per cent.) to make a fairly thick paste. 



2. The paste is transferred to a ball mill and ground for 24 hours, or, 

 until microscopic examination shows that the pollen grains are broken. 



3. Physiological saline solution is added and the resultant mixture is 

 centrifuged to remove insoluble debris. 



4. The extracted protein is purified by precipitation with acetone. 



5. The precipitate is dried and thus preserved until needed. 



6. For use, the precipitate is dissolved in physiological saline solution. 

 The amount of protein-nitrogen in this solution is determined by the 

 Kjeldahl method. 



7. The solution is then diluted so that each cubic centimeter will 



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