PrucccdUigs of the Ohio State Academy of Science 333 



damentally of the same nature as vegetative dimorphism. There 

 is nothing more extraordinary in the difference between male and 

 female or between the staminate and carpellate flower of a monoe- 

 cious plant than there is in the vegetative dimorphism to be seen 

 in such plants as the Mermaid-weed (Proserpinaca palustris), 

 Bidens beckii, or other similar forms. The same phenomena 

 are seen in the change of a root to a shoot or vice versa. Root 

 and shoot hereditary characters are present in both parts but 

 only one group is active under a given set of conditions. 



SEX RATIO. 



We are wont to assume that the ratio of the sexes is about 

 equal and this seems to be the case in the higher animals. For 

 some plants, however, it is very wide of the mark. Take for 

 example the gametophytes of Selaginella kraussiana : every cone 

 produces one megasporophyll and about i8 microsporophylls. 

 The number of microsporophylls varies somewhat. Now nor- 

 mally each megasporophyll produces four megaspores all from 

 one megasporocyte. There are several megasporocytes but one 

 destroys the others in its development. In the microsporangia, 

 on the other hand, there are numerous microsporocytes each of 

 which produces 4 microspores. The ratio between the spores 

 is therefore 4 : i8x4n, n representing microsporocytes. Roughly 

 speaking the ratio is sometimes as high as i :5000. Since the 

 megaspores produce females only and the microspores males 

 only, the ratio of the spores is also the ratio of the gametophytes 

 coming from them. Now this ratio, as will appear later, is fixed 

 by some process which takes place in the nuclei of the sporophyte 

 during vegetative growth before the reduction division has been 

 accomplished. 



In tlie case of the staminate and carpellate sporophytes of 

 the common hemp, the following condition has been found by 

 ordinary statistical methods. Hayer discovered by examining 

 40,000 plants of Cannabis that there were 100 staminate to 114.93 

 carpellate individuals ; Haberlandt in Austria found the ratio in 

 the same species to be 100 staminate to 120.4 carpellate plants; 

 while Fisch counting 66,000 ]:)lants at Frlangen found a ratio of 



