June 6, 1919] 



SCIENCE 



545 



seed infection by soil organisms during the 

 sensitive period of germination. 



On the other hand, experiments with wheat 

 seeds infected with the black-chafF organism 

 have sliown that this method used with for- 

 malin will completely destroy the organism on 

 the kernels. After screening and fanning to 

 remove shrivelled grains, the treatment should 

 be made by soaking infected seeds for ten 

 minutes in water then draining and keeping 

 moist for six hours. They are then soaked ten 

 minutes in formalin 1 :400 solution (1 lb. to 50 

 gallons of water) drained, and covered for six 

 hours; then dried over-night and planted next 

 day. If copper sulfate is used, the presoaked 

 seeds are thoroughly wetted in the 1:80 solu- 

 tion (1 lb. to 10 gallons of water) for ten 

 minutes, drained and kept moist twenty min- 

 utes, plunged for a moment into milk of lime, 

 dried over-night and planted. The effect of 

 the presoaking with water, besides preventing 

 seed injury, is to stimulate dried and dormant 

 bacteria on the seed coat, into vegetative ac- 

 tivity, thereby rendering them more sensitive 

 to the action of the disinfectant which must 

 be applied at the end of the presoak period and 

 of course before the seeds have begun to germi- 

 nate. This is fully in accord with the estab- 

 lished principle that microorganisms in a vege- 

 tative condition are more susceptible to de- 

 structive agents than when dry and in a rest- 

 ing stage. 



The effect of the presoak method of seed 

 treatment with chemical disinfectants is, there- 

 fore, two-fold — first, seed injury is prevented 

 by the dilution of the disinfectant as it enters 

 the presaturated seed tissues; second, the effi- 

 ciency of the disinfectant on the pathogen is 

 increased. In view of the fact that nine dif- 

 ferent varieties of wheat, also oats, barley and 

 maize, have been treated by this method, using 

 both formalin and copper sulfate, disinfectants 

 of widely different chemical nature, in strong so- 

 lutions (formalin 1 :320 and copper sulfate 1 :80) 

 without appreciable injury to germination, it 

 appears probable that the same physiological 

 principles here utilized can be applied to other 

 chemical disinfectants and to the treatment of 

 other seed-transmitted diseases amenable to 



control by these disinfectants, with variations 

 of course in the length of the presoak period 

 (which is six hours for wheat, barley and oats, 

 and ten to eighteen hours for maize) and of 

 the subsequent disinfectant period, as found 

 necessary for each kind of seed and pathogen. 



The use of this method in farm practise in- 

 volves no radical change in present procedure 

 other than to keep seeds moist for definite 

 periods before treatment. If the use of the 

 presoak method is found efficient for the 

 cereal smuts and other diseases as well as for 

 the black-chaff disease of wheat, it will result 

 in a saving of most of the seed now lost by 

 present methods of treatment and also in in- 

 creased germicidal efficiency. The formula- 

 tion of this method, as here reported and later 

 to be given in detail, opens up a wide field for 

 the reinvestigation of practical seed treatment 

 for the control of seed-transmitted diseases by 

 chemical disinfectants. Harry Braun 



Laboeatort of Plant Pathology, 

 BtTKEAu OF Plant Inddstet, 



U. S. DEPT. of AGBICm.TUEE 



THE AMERICAN PHILOSOPHICAL 

 SOCIETY 



The annual general meeting of the society was 

 held from April 2t to 26 and a program of over 

 fifty papers covering a wide range of subjects was 

 presented. The sessions were presided over by the 

 president, Professor W. B. Scott and by vice-presi- 

 dents G. E. Hale, H. L. Carson and A. A. Noyes. 



Two important features were a symposium on 

 the solar eclipse of June 8, 1918, and one on chem- 

 ical warfare. In the former special attention was 

 given to photographs and their interpretation of 

 the prominences and the coronal arches and 

 streamers obtained by members of the several ex- 

 peditions sent from the Lick, the Mount Wilson, 

 the Lowell, the Sproul and the Yerkes observatories. 



FBOORAU 



Thursday Afternoon, April 14, S o'clock 



William B. Scott, D.Sc., LL.D., president, in tha 



chair 

 The cosmic force, radio-action: Monboe B. Sntdeb, 



director of the Philadelphia Observatory. 

 The ooMervation of the natural monuments (illus- 

 trated) : John M. Cla&kb, director of depart- 



