MARCH 4, 1921 proceedings: WASHINGTON ACADEMY OF SCIENCES 115 



15 1st meeting 



The 151st meeting was held jointly with the Botanical vSociety of Washing- 

 ton in the Assembly Hall of the Cosmos Club on Thursday, December IG, 

 1920. Prof. H. M. Hall, of the Carnegie Institution of Washington, delivered 

 an illustrated address, entitled. Hay fever in its specific botanical relationships, 

 based upon studies carried out for a number of years in the Rocky Mountain 

 and Pacific coast states in cooperation with certain physicians and specialists, 

 especially Dr. Grant Selfridge, of San Francisco. 



Hay fever attacks about one per cent of the population of the United vStates. 

 It is not due simply to a local irritation, but to a general poisoning by toxic 

 albumins, derived usually from the pollens of various plants. The condi- 

 tions of attack are three: (1) a defective mucous membrane, permitting the 

 poison to gain access to the circulation; (2) a blood serum lacking in anti 

 bodies; (3) the presence of poisonous pollens in the atmosphere. 



A simple nasal operation frequently relieves the first-named condition. 

 The second is less accessible to treatment but mav be remedied by the in- 

 jection of solutions prepared from specific pollens. The third condition is 

 one to which practically everyone is exposed in the spring, summer, and fall, 

 since pollen is then extremely abundant in the atmosphere. Individuals 

 are more exposed to plant pollens than to any other nitrogenous substance, 

 with the exception of the food in the alimentary tract. 



Most plants do not cause hay fever, chiefly for the reason that they do 

 not produce wind-borne pollen. For example, of 1600 species of flowering 

 plants in the District of Columbia perhaps 300 are wind-pollinated. About 

 190 of the latter are grasses. Only about 50 are really abundant, and there- 

 fore to be considered first in a "hay fever survey." 



Many misconceptions have grown up regarding the sources of hay fever. 

 The spring type, often known as "rose cold," has no connection whatever 

 with roses. The common goldenrod is never known to cause hay fever, as 

 it produces very little pollen. It does, however, in common with many 

 other plants, carry on its surface considerable quantities of pollens that pro- 

 duce hay fever, such as that of the ragweed. Pines produce abundant pollen 

 but do not cause hay fever. 



Plants are tested for their capacity to produce hay fever, first, by the bo- 

 tanical method, as above noted, and second, by the injection of a pollen 

 extract into the skin. If the patient is susceptible to poisoning by a given 

 pollen a swelling and reddening are observed around the spot where the ex- 

 tract has been injected. 



The principal causes of spring hay fever are grasses, poplars and cotton- 

 woods, oaks, various nut-bearing trees (such as the black walnut, which is 

 a common source in the Sacramento Valley), the cultivated sycamore, the 

 Chenopodiaceae, and the plantains. In the late summer and autumn the 

 principal causes are ragweeds and other members of the ragweed tribe, the 

 artemisias, and some of the Chenopodiaceae. 



Successful treatment of hay fever depends upon close cooperation between 

 the physician, the botanist, and the laboratory technician. The possible 

 sources of infection in a given district must first be outlined by the botanist. 

 Pollen preparations are then made in the laboratory and these are used by 

 the physician in finding out to what pollens the patient is sensitive. Injec- 

 tions of dilute solutions of the specific causative pollens and of no others, 

 increasing from 1 : 300,000 up to as high as 1 : 1,000 or even higher, can then 

 be given before the hay fever season, and produce immunity for at least one 



