2 MITATIOXS, \AK1ATI().\S, AND RELATIONSHIPS OF TIIK OENOTHERAS. 



Guarded pedigree-cultures have Ixcn made from pure seeds of native species 

 of evening-primroses which had not previously been brought under close 

 observation, with a view to procuring additional evidence on mutability in 

 this group. 



The preliminary examination made it apparent that the group comprises a 

 swarm of clearly separable species, many of which had not been recognized 

 by the taxonomists and which gave basis for the current opinion as to the 

 wide variability of the common evening-primrose (0. biennis). 



The study of genetic relationships and of the phenomena of hybridization 

 in general has necessitated the organization of extensive cultures, which will 

 need continuance for two or more seasons before definite results may be 

 announced, and their discussion is reserved for a future paper. 



A few cases of fixed hybrids have been encountered, however, in which the 

 crossing of two species resulted in the production of a progeny consisting of 

 one fixed type constant in successive generations. Forms arising in this way 

 are. in reality, new species, and doubtless many such have arisen naturally 

 and now constitute a part of the native flora. 



Striking cases of vegetative mutation, or bud-sports, having arisen, atten- 

 tion has been devoted to a study of the inheritance of the saltatory groups of 

 characters. 



A systematic attempt to localize mutatory changes in the life-cycle of the 

 sporophyte has been made, and has met with marked success in a preliminary 

 way, since it has been possible to induce new mutants by the use of solutions 

 of strong osmotic activity and by highly dilute preparations of mineral salts, 

 some of which are poisonous to plants in high concentrations and stimulative 

 in low concentrations. Finally, an attempt has been made to bring the facts 

 disclosed in the descriptive part of the paper into correlation with prevailing 

 theories as to phylogcny and evolutionary procedure. 



The principal results were obtained from cultural investigations in the 

 experimental grounds and greenhouses of the New York Botanical Garden 

 and of the Station for Experimental Evolution at Cold Spring Harbor, Long 

 Island, and were also extended in the later stages to the Desert Botanical 

 Laboratory of the Carnegie Institution of Washington at Tucson, Arizona, 

 thus securing the advantages of a wide range of climate and soils. 



A note regarding the various mutants was presented at the weekly botanical 

 convention at the New York Botanical Garden, November i, 1905, and a 

 second one, dealing especially with sports or vegetative mutations, before the 

 Torrey Botanical Club, on November 4, 1905. A lecture dealing with his- 

 torical aspects of the phases of the subject imder investigation was presented 

 to the Barnard Botanical Club, December 18, 1905, in which the first announce- 

 ment was made of the induction of mutants by chemically and osmotically 

 active stimuli. A full description of the technique of pedigree-cultures and 



