[Vol. 2 



258 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



consisted in the successful introduction of various substances 

 into the neighborhood of the embryo-sacs at the time that 

 fertilization was imminent, and when the first trials were made 

 I had two main purposes in mind: first, to ascertain whether 

 or not foreign substances could be introduced into ovaries in 

 such manner as to affect the ovules with a minimum of trau- 

 matic effects, so that the ovaries might reach maturity; and 

 secondly, to ascertain whether or not such changes could be 

 produced in an early stage of sexual specialization, before the 

 development of the embryo-sac or after the union of the sexual 

 elements in fertilization. 



- 



The first results were obtained with pure strains of Oeno- 

 thera biennis and Raimannia odorata at the time mentioned, 

 but the transfer of my activities from the New York Botan- 

 ical Garden to the Desert Laboratory made it impossible to 

 carry out cultures of the progeny or to repeat similar experi- 

 ments upon this material. Meanwhile, Col. K. H. Firth, of 

 the Royal Medical Corps of (Jreat Britain, duplicated 1 my 

 general results with Raimannia and other plants in 1908, al- 

 though the fact that I had previously done this work was 

 unknown to him. 



New material was selected from the vicinity of the Desert 

 Laboratory and the tests were begun anew in 1906. The diffi- 

 culties to be overcome in such experiments are fully commen- 

 surate with the importance of the problem upon which they 

 bear. It is a necessary preliminary that the plants chosen 

 for the operations should be an elementary strain, a matter 

 which may need two or three years for determination, if not 

 already known. Next, not all ovaries will withstand the shock 

 and injury inflicted in the operations. The chances of ulti- 

 mate success will be greatest in many-seeded ovaries in which 

 the number, however, does not extend much beyond that of 

 ovules which may be affected by a single operation, giving 

 some opportunity for differentiation of effects and not entail- 

 ing large cultures. Lastly it is advantageous to deal with 

 perennial species which come quickly to maturity. This gives 



1 Firth, R. H. Roy. Med. Corps, Jour. 16: 4D7-514. 1911. 



