248 THE THEORY OF THE GENE 



strong females, and that weak females may fmiction as 

 females when opposed to strong males. To what extent 

 these relations may be affected by age-factors (settling 

 down, for example), or by environmental factors is not 

 entirely clear, although Hartmann's statement that the 

 relations hold from day to day as the swarm-spores are 

 tested seems to exclude such explanations. Unfortunately 

 the material is not suited to a genetic analysis of the fac- 

 tors involved. Whether the quicker settling down of the 

 gametes from a certain individual is a sufficient index of 

 their ''sex" and if so, how this is changed when a weak 

 female acts as a male, etc., is not apparent. Nevertheless 

 the failure of gametes from the same plant to copulate 

 appears to put the phenomenon in the same category as 

 self-sterility and its correlative cross-fertility. To desig- 

 nate this as a criterion of sex is perhaps largely a matter 

 of choice or of definition at present. Personally, it seems to 

 me to confuse rather than to clear up the problems in- 

 volved to use the word sex in this connection where the 

 phenomenon is one of union or non-union of gametes 

 rather than one of sex as commonly understood. 



The question then may be asked whether it may not 

 be simpler and less likely to lead to confusion to call the 

 factors, involved in the miion of the mycelia of Coprinus 

 and of the swarm-spores of Ectocarpus, self-sterility fac- 

 tors rather than sex-factors. The recent important results 

 of East in his studies on self-sterility in tobacco have for 

 the first time put the oft-studied problem of cross- and 

 self-fertility in flowering plants on a well-tested genetic 

 basis. These phenomena in the flowering plants have many 

 resemblances to the union of the gametes in Coprinus and 

 Ectocarpus and while the modus operandi of the process 

 may not be identical in all cases, there is much to suggest 

 that the genetic and physiological backgrounds may be 

 essentiallv alike. 



