Proceedings of the Ohio State Academy of Science 339 



tary characters are present which are able to produce the stami- 

 nate or the carpellate condition or both on the same individual. 



In most of the monoecious and diecious flowers also there 

 are some vestiges of the opposite set of organs. The gameto- 

 phytes of heterosporous plants are however all strictly unisexual 

 The nature of the spore determining the condition definitely 

 and this unisexuality is produced entirely apart from the re- 

 duction division. 



In Salix petiolaris, Chamberlain found microsporangia 

 growing in the ovulary of the carpel. In the microsporangia 

 borne inside of the ovularies the microspore development was 

 sometimes normal, but was as often feeble and abortive. In 

 ovularies which contained microsporangia, the o"\fules were 

 sometimes orthotropous, and had the integument developed all 

 around. . The megaspore development was normal and embryos 

 were not uncommon. Now this is certainly an important case, 

 for it shows that even in the very organs differentiated to pro- 

 duce the one or the other set of spores, the hereditary charac- 

 ters are not always completely controlled. Something over- 

 comes the dominance of the characteristic tendency and thus 

 permits the opposite tendency, which has no phylogentic basis 

 in the hereditary characteristics of the organ, to come to ex- 

 pression. But this is after al-1 no more remarkable than many 

 other vegetative expressions, as stamens changing to petals, 

 leaf-blades of Botrychiums developing as sporophylls, and many- 

 other peculiar developments that might be mentioned. 



One of the most interesting cases on record in the change 

 of the sexual condition is that of the tropical papaya (Carica 

 papaya). This is a dioecious species but it has been found that 

 if one of the staminate and therefore unfruitful trees has its 

 terminal bud removed it soon begins to produce carpellate fruits.. 



This experiment suggests that there may be many methods 

 of manipulation, which might be employed for changing the 

 sexual condition, that have not yet been tried on favorable sub- 

 jects. 



Braem reports a somewhat similar case for a worm. 



