580 



SCIENCE 



[N. S. Vol. XLII. No. 1086 



sand imbedded in tlie outer part of the epi- 

 dermis, and apparently thoroughly encased. 



This feature is quite obviously the result of 

 the nature of the water in which the shells 

 grew. There is no lime to be had save what 

 little weathers out of the felspar of the coun- 

 try rocks: as these are largely soda felspars, 

 this amount is indeed small. 



If this be a variety worthy of a name, I 

 would suggest that it be called Unio com- 

 planatus var. mainensis. It seems to be a 

 form native to the granitic region of New 

 England, and so far as I know is found 

 mainly in western Maine. It is common 

 throughout the ponds and lakes of Oxford 

 county in that state. Since 1909 it has become 

 so plentiful in Songo Pond that one can pick 

 up ten dozen in half a hour, within three hun- 

 dred feet along the beach. I have been in the 

 habit of gathering it to boil for eating: it is 

 quite palatable if cooked just the right time 

 and with much salt. 



My thanks are due to Dr. L. P. Gratacap, of 

 the American Museum of Natural History, for 

 aid in determining the shells, and to Professor 

 F. Loomis, of Amherst College, for suggest- 

 ing that the variety might be of general 

 interest. Stephen G. Rich 



Ithaca, N. Y. 



THE AMERICAN PHYTOPATHOLOGICAL 

 SOCIETY 



A SPECIAL MEETING of the Am erican Phy- 

 topathological Society and its Pacific Division, 

 was held at the University of California, from 

 August 3 to 5. Addresses of welcome were 

 delivered by Dr. Herbert J. Webber, director 

 of the Citrus Experiment Station and Dean 

 of the Graduate School of Tropical Agricul- 

 ture, Riverside, California, and Professor E. 

 E. Smith, president of the Pacific Division of 

 the society. 



Dr. Haven Metcalf responded for the so- 

 ciety. 



The following program was presented: 

 International Phytopathology: Otto Appel, 



Dahlem, near Berlin, Germany. (Eead by 



Dr. C. L. Shear. This will be published in 



full in Phytopathology.) 



Pythiacystis Infection of Deciduous Nursery 

 Stock: E. H. Smith, University of Cali- 

 fornia, Berkeley, Calif. 



A dieback of young deciduous trees, which 

 occurred extensively in northern California 

 the past two seasons, has been traced to a spe- 

 cies of Pythiacystis, morphologically identical 

 with P. citrophthora. Most of the root stock 

 is apparently immune, but above the bud the 

 bark is infected in one to several cankers, 

 which often girdle the tree and kill back the 

 whole top. Profuse gumming occurs. The 

 fungus has been isolated from peach, almond, 

 pear and plum, and the disease produced by in- 

 oculation in apple, pear, peach, almond, apri- 

 cot, prune and cherry, all from one-year-old 

 stock. Similar cankers have been produced 

 by inoculation with P. citrophthora isolated 

 from lemon fruit. A pythiaeeous fungus has 

 been twice isolated from almond cankers and 

 successfully inoculated into almond, which 

 readily develops an oospore stage. This has 

 different characters of growth from the orig- 

 inal strain, and a less degree of pathogenicity, 

 but may ultimately be placed in the same spe- 

 cies. 



Two Eastern Forest Diseases which Threaten 

 the Pacific States: Haven Metcalf, U. S. 

 D. A., Washington, D. C. (with lantern). 

 The speaker exhibited lantern slides and 

 specimens of the chestnut-bark disease 

 (Endothia parasitica) and the white-pine 

 blister rust (Cronartium riiicola). The 

 danger which these diseases present to the cul- 

 tivated chestnut of the Pacific states and to 

 the native stand of five-leaf pines was indi- 

 cated. Especially to be considered is the 

 danger to the very valuable species Pinus 

 lainbertiana and P. monticola. The speaker 

 advocated rigid state quarantines against nur- 

 sery stock of the genus Castania, the 5-leaf 

 species of pines, and the genus Rihes. 



Beet Blight : E. E. Smith, University of Cali- 

 fornia, Berkeley, Calif. 

 Specimens of diseased beets were exhibited 



and the methods being employed in the study 



of the disease were explained and illustrated. 



The structure of the diseased beets was dis- 



