218 THE THEORY OF THE GENE 



male and female elements, and both produce eggs and 

 sperm-cells; but the number of female organs (arche- 

 gonia) and of male organs (antheridia) and their time of 

 appearance show characteristic differences. 



The Marchals had obtained, as has been said, the dip- 

 loid FM gametophyte in the same species used by Wett- 

 stein, and had shown that it produces both female and 

 male organs. Wettstein confirms this and reports that the 

 male organs develop before the female. 



A comparison of the three types, FM, FFM, FFMM, 

 is interesting. The FM plant is strongly protandric. At 

 first there is a great excess of antheridia or male organs 

 compared with archegonia. The archegonia develop later. 



The FFMM plant is, as Wettstein says, twice as 

 strongly protandric as the FM plant. At first only anthe- 

 ridia appear. Very late in the year, when the old anthe- 

 ridia have gone, a few young archegonia appear — some 

 plants never develop them. Still later a vigorous develop- 

 ment of female organs may set in. 



The triploid plants are protogynic. At least, at the time 

 when the FFMM tetraploid plants have only male organs 

 (in July), the triploids have only female organs. Later 

 (in September) both organs are present. 



These experiments are interesting in showing how arti- 

 ficial hermaphroditic individuals may be made from 

 plants that normally have separate sexes by combining 

 the two sets of elements. The results also show that the 

 sequence in which the sexual organs develop is deter- 

 mined by the age of the plant. More important is the 

 actual reversal of this time relation by changing the 

 genetic composition in the opposite direction. 



