PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



THE BOTANICAL SOCIETY OF WASHINGTON 



The 135th regular meeting of the Society was held in the Assembly 

 Hall of the Cosmos Club at 8.00 p.m., Tuesday, April r, 1919; 65 mem- 

 bers and 5 guests being present. 



Under "Brief Notes and Reviews of Literature," Prof. A. S. Hitch- 

 cock exhibited a volume on "A Monographic Study of the Hawaiian 

 vSpecies of the Tribe Lobehoideae," by Prof. Joseph F. Rock. Mr. 

 Walter T. Swingle announced that, while he was in China, he pur- 

 chased for the Library of Congress a large collection of Chinese books, 

 mostly on natural history. 



In a paper on A poisonous milkweed, Asclepias galioides, Dr. C. 

 DwiGHT Marsh gave briefly a history of the loss of sheep in Colorado 

 caused by the eating of the whorled milkweed. He stated that this 

 plant had never been definitely recognized as having a toxic character, 

 but careful feeding experiments demonstrated that it is exceedingly 

 poisonous, not only to sheep, but to cattle and horses. A study of the 

 distribution and habits of the plant shows that the problem of control 

 is one of peculiar difficulty, for in certain irrigated regions, particularly 

 in Colorado, this species is spreading with great rapidity. 



Dr. C. H. Kaufman gave a paper on The genus Cortinarius, in which 

 he described some of the typical species of the group. The lantern 

 slides that were used were very instructive on the color and form of these 

 brown-spored agarics. He stated that the genus contained over 500 

 species, of which 200 species have been recognized in the United States. 

 They occur most abundantly in the temperate and colder zones, or in 

 the higher altitudes, being found abundantly northward to the limits 

 of forests and at elevations to the edge of the timber-line. Some 

 species are intimately connected with roots of forest trees, and individual 

 species are limited to special kinds of forests. They develop late in the 

 season, preferring as a rule, the cooler months. Many of these species 

 are highly colored and, as far as known, all are edible. 



A joint paper on A physiological study of Pythiuni debaryanum Hesse 

 on the potato tuber was given by Drs. Lon A. Hawkins and Rodney B. 

 Harvey, in which it was shown that there is a correlation between the 

 resistance of the tissue of the potato to puncture and the resistance to 

 infection by the fungus. The paper was illustrated by motion photo- 

 micrographs showing the penetration of the cell walls of the potato by 

 the fungus. 



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