138 



produced. During August and September sunlight is barely sufficient to 

 produce maximum dry weight and from October to March sunlight definitely 

 limits dry weight production. We cannot compete with the enormous energy 

 of sunlight by growing plants in basement rooms under all artificial light. 

 The best arrangement at present is to use sunlight in a greenhouse while it 

 lasts, and to supplement for a period of three to five hours each night with 

 artificial light. For this work the most practical method is to use 500-watt 

 tungsten filament lamps spaced at distances of three to four feet along a three- 

 foot growing bench. The period of burning of the lamps can best be regu- 

 lated by a thermostat which lights the plants intermittently in intervals of 

 about ten minutes on and ten to thirty minutes off all during the night. The 

 off period is determined by the rate of heat loss to the outside atmosphere 

 and varies mainly with the outside temperature. This system of lighting can 

 be used with plants which require a low temperature since the heat output of 

 the lamps is closely controlled. Such plants as gladiolus, calceolaria, carna- 

 tion, gardenia, hyacinth (following a three-months' cold treatment), lily, 

 orchid, and strawberry respond well to such intermittent lighting. Crassiila 

 ruhicimda and digitalis were also brought into flower following a five-months' 

 low temperature treatment. 



In the search for a more ideal light source for growing plants entirely 

 with artificial light, a lighting unit consisting of four sodium vapor lamps 

 supplemented by either three 60-watt Mazda or one 400-watt capillary mer- 

 cury lamp gave good results with gladiolus, cotton, and geranium. The plants 

 were exposed continuously (for a whole year in some cases) to the sodium 

 vapor lamps, while the supplemental Mazda or mercury lamps were burned 

 intermittently for three-fourths of an hour twice each morning and again 

 twice each evening. The temperature was regulated accurately at 63° F." 



After the meeting adjourned at 4:30 P.M. tea w^as served by 



the New York Botanical Garden. „ „ 



Clyde Chandler 



Recording" Secretary 



Minutes of the Meeting May 7 



The meeting, held at the American Museum of Natural History, 

 was called to order by the President at 8:15. 



Eighty-six persons were present. 



The minutes of the meeting of April 17 were adopted as read. 



Due to the absence of the secretary the president appointed the 

 vice-president, Mr. Hastings, to act as secretary for the meeting. 



The following were elected to membership in the Club : 



Annual: Miss Marie B. Clark, 1420 Duncan St., N. E., Wash- 

 ington, D. C. ; Dr. Ralph Emerson, Biological Laboratories, Har- 

 vard University, Cambridge, Mass. ; Miss Louise Eden Guild, Mile- 



