The Gamelophyte in Inhentance 129 



fore, that there would be the following outstanding character- 

 istics of inheritance in ganietophytes. (i) There could be no 

 possibility of dominance, since but one representative of an allclo- 

 morphic pair could be present. Any discovery of blending inherit- 

 ance in gametophytes (with respect to a monoh\'brid situation) 

 would serve to cast doubt upon the Mendelian mechanism. (2) 

 Clear segregation would appear in the first generation following 

 the cross and the phenot^-pic ratios would be quite different from 

 those encountered among sporophytes. 'I'he various factor t>pes 

 might, of course, be expected to operate, but again the ratios 

 obtained would be unusual. All of this, however, is little more 

 than idle speculation, serving merely to point out discoveries that 

 might be expected in the future. 



A study of inheritance in gametophytes might be profitable 

 for other reasons also. Among those higher plants which have 

 been the objects of genetical research, the sex act is a very well- 

 insulated performance, occurring deep within the tissues. Fur- 

 thermore, it is both prefaced and followed by quite a sequence of 

 events, which we know must be taking place with considerable 

 regularity but which we cannot control. Surely there would be 

 much greater hope of any artificial manipulation of the sex act, 

 making possible a more critical study of the germ plasm, in those 

 organisms where the gametes themselves could be manipulated. 

 It would seem that such things might be possible in those lower 

 plants where the gametophyte is the dominating generation, 

 although the technique necessary for such experiments would 

 doubtless be difficult to develop. 



The actual work that has been done on inheritance in game- 

 tophytes is practically nil. Pure line studies have been made in 

 a number of thallophytes, selection has been attempted, and 

 some mutations have been found, but none of the experiments 

 has revealed anything critical on the matter of segregation of 

 characters following a sex act. 



Transeau (2) has made some observations on ll\c green alga 

 Spirogyra, which, while they did not involve any experimental 

 work, were nevertheless quite suggestive. This author was famil- 

 iar with several species of Spirogyra in their natural habitats, and 

 noted several natural populations which were clearly mixtures of 



