176 TORREYA 



years and delegate of the Club for several years on the Council of the New York 

 Academy of Sciences and to the Council of the American Association for the Ad- 

 vancement of Science. He was Vice-President for fourteen years, from 1917 to 

 1941, and served the Club well as its President during the year just previous to his 

 ' death. 



In recent years it had been the custom of the Club to hold its first fall meeting 

 at the Brooklyn Botanic Garden, at which time members were given an opportunity 

 to report on their work during the summer period. Those who attended these meet- 

 ings will long remember the cordiality and sincerity of his greeting which always 

 left one with the impression that in him one had a very warm personal friend. 



As a token of appreciation of the importance of his contributions to our knowl- 

 edge of plants and recognition of his administrative abilities, and also for his ex- 

 ample of right living, it is directed that this memorial be published with the minutes 

 of this meeting and a copy sent to members of the bereaved family. 



(Signed) Sam F. Trelease 



P. W. ZllMMERMAN 



Arthur H. Graves 



B. O. Dodge, Chairman. 



After Dr. Dodge so moved, the Memorial was accepted by a rising vote of the Club 

 members. 



The scientific program was presented by Dr. Michael Levine, who spoke on "The 

 combined effects of colchicine and x-rays on onion root tips." 



Fifteen series of experiments were made in which six to forty onions (Allium 

 cepa var. Yellow Globe or var. Brigham Yellozu Globe) were used in each. The 

 bulbs were selected for their uniformity of weight, size and freedom from fungus 

 diseases. The bulbs were placed in water for periods of three to twelve days to in- 

 sure an adequate number of roots. The bulbs were then placed in a 0.01 per cent 

 aqueous solution of colchicine and after 6,18,24,36,48,72,96,125, or 140 hours of 

 exposure were removed and washed in running water. After each given exposure, be- 

 ginning with the 18 hour treatment the bulbs were divided into two groups of equal 

 number. The f^rst group was returned to fresh water, the second group was ex- 

 posed to x-rays. A third group, not treated with colchicine, was irradiated simul- 

 taneously with the second group ; both groups were then returned to water. A fourth 

 group of bulbs was kept in water. The x-ray treatment consisted of a single exposure 

 for 11 to 30 minutes during which time 900, 1500 or 3000 roentgen units (r) were 

 delivered. 



The roots of the four groups of bulbs were examined daily and photographed at 

 frequent intervals. Selected root-tips from all the bulbs were prepared for micro- 

 scopical examination. Root-tips exposed to colchicine for 72,96,125, or 140 hours and 

 irradiated with 900 r when returned to water failed to grow. Root-tips exposed to 

 colchicine for 24 to 48 hours and irradiated with 900 r showed temporary growth 

 inhibition and resumed growth as indicated by the prolongation of the tips below the 

 swellings induced by the colchicine. With larger doses of x-rays, 1500 r and 3000 r, 

 roots colchicinized for 36 to 48 hours failed to resume growth for 14 to 21 days after 

 their return to water. 



The microscopical examination of these arrested tissues showed progressive 

 coagulation and destruction of the nuclear materials of the cells in the root-tips. 

 The root-tips colchicinized only were studied concurrently but showed complete re- 

 covery when returned to water. The roots irradiated, only showed temporary arrests 

 of growth. With the higher doses of x-rays some injury was noted but growth was 

 halted temporarily. 



Acenaphthene used in lieu of colchicine had no effect on the activity of the x-rays. 

 Roots so treated behaved like those non-chemically treated. 



The combined effect of colchicine and x-rays was also studied on the growth of 

 leaves of the onion of the Brigham Yellow Globe variety. The leaves of the col- 

 chicinized bulbs showed little growth after irradiation with 3000 or 1500 r. While 

 the plants x-rayed only showed some leaf growth but less than that which occurred in 

 normal or colchicinized bulbs. The latter two groups showed little difference between 

 them. 



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