107 



Mr. Clarence Lewis, 1000 Park Avenue, New York City, and 

 Miss Dorothy V. Smith, 138 East 94th Street, New York City, 

 were unanimously elected to membership in the Club. 



Dr. John M. Arthur of the Boyce Thompson Institute for 

 Plant Research in Yonkers gave an interesting talk on "Some 

 Effects of Visible and Invisible Radiation." His talk was illustrated 

 by a large number of lantern slides. He showed that Salvia 

 flowers best with a day length less than seventeen hours. Lettuce 

 flowers only with a day exceeding twelve hours in length. Buck- 

 wheat was unaffected by day length, growing even better with 

 twenty-four hours of illumination than with ordinary light and 

 darkness. Geraniums grew and flowered best with eighteen hours 

 of light and extra carbondioxide (ten times the strength ordi- 

 narily found in the air). Tomato in contrast with buckwheat 

 flowered best with eighteen hours of light, twenty-four hours of 

 illumination being injurious. With continuous illumination toma- 

 toes accumulated large amounts of carbohydrates and were defi- 

 cient in nitrogen. He also showed the effects of different portions 

 of the solar spectrum on the growth of plants. In blue light only, 

 four o'clocks were very deep green in color but much dwarfed in 

 spite of the fact that the light was reduced only 10 per cent of the 

 energy value of sunlight. In red light of 37 per cent strength, 

 the same kinds of plants were etiolated. Petunias showed the same 

 sort of response. 



Ultra-violet light which has been so widely exploited as bene- 

 ficial to man and domestic animals proved definitely injurious to 

 plants when the wave lengths were shorter than those encountered 

 in daylight. Even the wave length of 285 millimeters, only five 

 millimeters shorter than those found in ordinary daylight in- 

 jured plants after fifty hours' exposure. Where the reduced in- 

 tensities of light were the same composition as sunlight most of 

 the plants thrive best and made the greatest dry growth with 

 78 to 35 per cent of full sunlight. Tomato and tobacco proved to 

 be shade, plants thriving best with only 35 per cent full light. Dr. 

 Arthur also gave a very interesting report on the reddening of 

 apples. The Macintosh apples grown in New York State are many 

 of them poorly colored. He found that by exposing them to sun- 

 light soon after harvest in August or September, they developed 

 a good red color, but if exposed under window glass no such 

 color developed. Light from the mercury arc lamp injured the 



