SCIENTIFIC PROCEEDINGS. 



Abstracts of Communications. 

 Sixty-first meeting. 



Cornell University Medical College, October 21, 1914. 

 President Lusk in the chair. 

 1 (933) 



The effect of potassium iodide, methylene blue and other sub- 

 stances applied to the embryo sacs of seed-plants. 



By D. T. MacDougal. 



[From the Desert Laboratory, Tucson, Arizona.] 



The results of some experiments at the New York Botanical 

 Garden in 1905 showed that it was possible to introduce foreign 

 substances into the ovaries of the higher plants, in such manner 

 that the egg, or pollen-nuclei, were affected as to their genetic 

 capacity. 



Similar results were achieved independently four years later 

 by Major Firth, of the British Royal Army Medical Corps, Dr. 

 Firth being unaware of the previous discoveries. 



The removal of my work to the Desert Laboratory in 1906 

 made it necessary to find new experimental material. Species 

 suitable for the study of the modification of the germ-plasm by 

 external agencies should be genetically simple, and preferably 

 perennial, so that successive generations may be kept alive for 

 comparison, and it is a great advantage if the plant can be brought 

 to maturity in a single season. 



Many-seeded ovaries, with the ovules standing in an open 

 chamber, offer the best mechanical features, and naturally, only 

 those which will recover from the traumatic effects of the neces- 

 sary operations are of value to the experimenter. The above 



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