Proceedings of the Ohio State Academy of Science 335 



In the pine which is monoecious, the staminate cones are 

 greatly in excess of the carpellate and the enormous difference 

 in the number of male and female gametophytes is again, as 

 in Selaginella, determined by the spores which in turn are pre- 

 determined in the floral branches. For normally all the sporo- 

 phylls of a cone are of one type. Here then the future sex is 

 determined even in the incipient flowers from their very nature 

 and position on tlie branch. In rare cases the determination 

 may not be complete. Part of the cone may be carpellate and 

 part staminate as reported by Fischer. Here the fixing of the 

 sex tendency was evidently delayed to a later stage than usual. 



In the flowers of the higher plants, the organs which pro- 

 duce the spores in which the sex of the gametophyte is deter- 

 mined are sometimes varialjle and sometimes constant. In the 

 lower forms the numbers are usually exceedingly variable, as 

 for instance in Sagittaria latifolia. In the more highly devel- 

 oped forms the numbers are very constant as in a lily where 

 there are nearly always six stamens to three carpels. Since 

 the males produced in a stamen are fairly constant in number 

 and also the females in the carpels the sex ratio of the gameto- 

 phytes would be 6 x males : 3 y females, x being a much larger 

 number than y. 



The ratio of Selaginella kraussiana has been given above. 

 On some Selaginellas as S inaequalifolia, according to the illus- 

 trations, the number of microsporophylls and megasphoro- 

 phylls seems to be about equal. Here then the proportion of 

 females to males produced must be much larger than in S. 

 kraussiana, provided the microsporangia produce appro.ximately 

 equal numbers of spores in the two species. Selagnella rupes- 

 tris, according to Miss Lyon, produces strobili or cones on the 

 new vegetative shoots in late summer and autumn. Only mega- 

 spores develop that season and in tliese the gametophytes reach 

 the stage bearing archegonia. In the spring the cones resume 

 their special growth and the first microspores appear. Thus 

 each cone has a basal zone of megasporangia, approximately six 

 months old, and above it a narrow region of microsporangia. 

 The number of microsporangia appears to be strictly limited, 



