28 



'Mr. John T. Presley, Sacaton, Ariz., was elected by unanimous ballot 

 to annual membership. 



The scientific program consisted of three talks. The first 

 speaker, ]\Ir. Robert Hulbary, discussed "A fungus disease of 

 Austrian pine." The speaker's abstract follows : 



In blighted needles of Austrian pine collected in northern Illinois in the 

 fall of 1938, immature stromata indicated the cause of the blight. Infected 

 needles were wintered out-of-doors and examined periodicals^ The stromata 

 remained quiescent through the winter but ver\- early in the spring began to 

 develop and by ^March 1 had emerged as strongly erumpent, loaf-shaped 

 structures. A month and a half later, pjxnidial locules were becoming dif- 

 ferentiated, and by May 15 conidia were being produced. 



The distinctive dothideaceaceous structure of the stroma distinguished 

 the fungus from every described group. For it the new genus Dothisfroina 

 is proposed. 



The well-marked dothideaceous structure of the stroma and the spore 

 characters place the new fungus in the scolecosporous group of the Phoma- 

 ceae close to Hemidoihis Sydow. and Scptocyta Petrak. 



The second speaker. 'Mr. John Dodd, discussed "Some reactions 

 to grafting in J'^iola." 



The third speaker. Dr. Sydney Greenfield, discussed ''Chemical 

 inhibition of photosynthesis."' The speaker's abstract follows : 



The rates of photosynthesis as measured by oxygen evolution in War- 

 burg manometers were determined with Chlorclla vulgaris cells pretreated 

 with solutions of various inorganic compounds, and compared with control 

 rates. Several substances, including ZnSOi, CuS04, (XH4)oS04, H3BO3, 

 XiSOi, C0SO4, KCl, KI, and HgCU were found to inhibit photosynthesis, 

 whereas others like MnSOi, KXO3, and MgS04 did not retard the process. 

 Inhibition was studied at five light intensities, from a range where light was 

 limiting to where it was in excess, in order to determine the effects of these 

 inhibitors on the photochemical and dark reactions in photosynthesis. A 

 comparison of control and pre-treated cell rates revealed differential inhibi- 

 tion. ZnSOi, XiS04, and KCl were found to inhibit the dark reaction with- 

 out appreciably affecting the light stage. CUSO4, H3BO3, and KI inhibited 

 the dark reaction but also retarded the light reaction to a lesser extent. 

 (XH4)2S04 and C0SO4 caused a relatively equal inhibition of both reac- 

 tions. X'o substance was found which inhibited the light reaction alone. 



The meeting adjourned at 4:40 P.]\I. to enjoy the deHcious 

 refreshments provided by members of the Garden staff. 



Respectfully submitted, 



JOHN W. THOMPSOX, JR. 

 Recording Secretary 



