322 CARNEGIE INSTITUTION OF WASHINGTON. 



Rocky Mountain and Mississippi Valley Regions by F. E. Clements, W. V. Mullin, 



R. J. GiLMORE, AND J. H. C. SmITH. 



Excessive rainfall over much of the Middle West prolonged the flowering 

 period for the most important hay-fever plants and correspondingly increased 

 the growth and pollen production. Daily analyses of the pollen-content of 

 the air were made at Colorado Springs, whenever the weather conditions per- 

 mitted, by means of an anemometer which measured the air passing over 

 pollen-plates as an automobile was driven through the district to be tested. 

 This preliminary study warrants the following conclusions: (1) rain clears 

 the atmosphere of pollen grains; (2) the amount of pollen in the air varies 

 with the velocity of the wind; (3) the pollen in the air reaches a maximum 

 within 1 to 3 hours after the anthers have shed. This maximum usually 

 falls between 8 and 11 o'clock in the morning, but is affected to some extent 

 by the air-currents. 



In connection with the vegetation studies being made throughout the 

 West, a survey has been begun of the detailed distribution of wind-pol- 

 linated species, especially along roadsides and in the vicinity of towns. While 

 the most important species are more or less generally present in a particular 

 state or region, they may range from dominant to absent in any particular 

 locahty, and a knowledge of their exact location and abundance is alone of 

 practical value to the physician or hay-fever patient. 



Among the clinical results of the year perhaps the most interesting dealt 

 with sensitivity to different pollens in regard to the evolutionary relation- 

 ship of the species concerned. While four species of sagewort, Artemisia, 

 belonging to three different sections of the genus, are abundant in the vicinity 

 of Colorado Springs, one of them, A. campestris, appears to suffice for the 

 diagnosis and treatment of hay-fever due to any of the group. On the other 

 hand, there is usually a difference in the intensity of reaction to the three 

 species of Ambrosia, and a number of patients react to one but not to the other. 

 Patients sensitive to Ambrosia regularly respond to the related genera, Iva and 

 Franseria, though in varying degree. Among the goosefoots, the Russian 

 thistle (Salsola) and lamb's-quarters (Chenopodium) , although not closely 

 related in the same family, possess pollen grains all but identical in appearance 

 and are equally effective, though about one-fifth of those treated react to one 

 and not to the other. The related summer cypress {Kochia) is less than half 

 as effective, probably because of its less abundance. Three-fourths of 

 those tested during the season reacted to the pollen of four or more species, 

 while one-fourth responded to but three pollens or less, five alone being sensi- 

 tive to a single one. The advantages of pre-seasonal treatment are brought 

 out clearly by the fact that this yielded an average relief of 90 per cent, in 

 contrast with 50 per cent for seasonal treatment, though this also gave com- 

 plete relief in some cases. The necessity for the use of local survey and pollen- 

 plates in complete diagnosis is well illustrated in the case of a patient who 

 had always resided in Colorado Springs but failed to react to the pollen 

 extracts of 29 species occurring there. 



On the chemical side a considerable number of pollens have been analyzed 

 with respect to their composition, especially as to albumins and globulins, 

 and prehminary attempts have been made to determine the precipitation 

 effects of these and of the various pollens. 



