MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 87 



induced consist in the suppression of some qualities of the parental form and 

 the substitution therefor of other characters with which the suppressed 

 features are mutually exclusive. The changes are expressed in anatomical 

 alterations and modifications of attendant functions. 



Atypic derivativesjiave been secured in this manner from two species, 

 Raimannia odorata and Oenothera biennis, by the use of more than one reagent, 

 as described in the preceding text. The induced mutants have been tested to 

 the second and third generation, with the result that both are found constant 

 in the sense that they do not intergrade back to the parental form. 



The injection of the solutions into the ovaries results in the total destruction 

 of some eggs by the mechanical action of the needle and of the solution itself, 

 while in a few the stimulative or other action is of such nature that the changes 

 are induced which result in the modification of the hereditary characters and 

 of the adult sporophytes which carry them, while doubtless in most of the 

 cases no action at all resulted. Of course in some of the unsuccessful tests all 

 of the ovules were destroyed and fell off before maturity. While it seems 

 more natural to assume that the injection results in direct action of the fluids 

 on the egg-cells, yet the possibility is by no means excluded that the saturation 

 of the tissues of the ovary with the solution results in the induced effect being 

 due directly to the action of the reagent upon the advancing pollen-tube and 

 its contents. 



The wide variety of substances used as reagents in securing the alterations in 

 question makes it impossible to suggest the nature of the changes induced in 

 the reproductive elements, since the actual effect may be osmotic or chemical. 

 Neither may it be said whether the changes consist in disturbances of the pro- 

 cessions of enzymatic action, or actually modify the structure and composition 

 of the cytoplasm or nuclear constituents. 



Mutants have thus been produced by conditions brought about in an exper- 

 imental way, and it can not be denied that similar action of external forces 

 might occur unaided by man. The radioactivity of spring and rain water, or 

 the effects of corrosive or other gases which are being set free in numberless 

 places on the earth's surface, might produce effects similar to these obtained 

 in the pedigreed cultures. Undue or abnormal secretions from the walls of the 

 ovary, from neighboring tissues, or from' intruding foreign pollen incapable 

 of accomplishing fertilization might exert a similar influence. The stings and 

 lacerations of insects and animals and the action of parasitic fungi are known 

 to be accompanied by the liberation of certain substances, the activity of 

 which results in profound changes in the somatic tissues. It is not unrea- 

 sonable to suppose that the effect of these substances upon the ovary might 

 exert equally important changes in the egg apparatus or developing ovules. 

 In its present state this investigation appears to be of great potential impor- 



