28 



The Histoey and Control of Sex. 



David M. Mottier. 



The student of sex and closely related problems of heredity may ra- 

 tionally ask himself any or all of the following questions : What is the 

 significance of sex? or, in other \A-ords, why are organisms male and female? 

 Is the sex of the organism determined during the early development of the 

 individual? or is it predetermined in the germ cells? If the former, what 

 conditions of the environment are favorable to the development of males 

 and what to females? If the latter, what is it in the gametes or sex-cells 

 that predetermines maleness or femaleness? 



As in the establishinent of the doctrine of sexuality itself, these ques- 

 tions can be answered by exjjeriment only and by the microscopic investiga- 

 tion of the germ cells and the manner of their development. As an intro- 

 duction to what I shall have to say in this paper concerning sex control, I 

 desire to pohit out briefly those lines of study which seem to me to have 

 been most effective in establishing the doctrine of sexuality in plants ; for 

 it will be seen that the lines of investigation which established the theory 

 of sex are similar to those that are yielding the most fruitful results in 

 the study of the more difficult hereditary problems of the present day. 



When in rhe history of civilized or semi-civilized man, the idea arose 

 that plants possess sex, no one can tell or perhaps imagine. Before the 

 days of written history the old Arabs of the desert knew that certain palm 

 trees produced fruit, while others did not, and, in order that the fruit 

 miglit develop abundantly, it was necessary to bring the flowers of the 

 sterile trees and hang them upon the branches of those which bore the 

 fruit. It is evident that they also practiced the caprification of the fig, 

 using the same methods employed at the present time in the fig-growing 

 localities along the Mediteri-anean, for we read in Herodotus who, in speak- 

 ing of the Babylonians, states that. "The natives tie the fruit of the male 

 palms, as thej- are called by the Greeks, to the branches of the date-bearing 

 palm, to let the gall-fly enter the dates and ripen them, and to prevent the 

 fruit falling off. The male palms, like the wild fig trees, have usually the 



