SEXUALITY AND THE ENVIRONMENT. 2o7 



carpels of which were somewhat dissociated. On the upper 

 half they were entirely male. He did not succeed in impreg- 

 nating any of the numerous and well-formed ovules. He 

 observes : " This well-authenticated case also favours the 

 theory that vigour in the plant is productive of the female 

 line of vital force." * 



It is a common phenomenon for diclinous trees to change 

 their sex in diiferent places or seasons. Ashes and Maples, 

 as well as Palms, have been known to do this. The only in- 

 terpretation being apparently the difference which occurs in 

 the climatal conditions from year to year, or the modifications 

 of temperature, soil, etc., consequent on different environing 

 circumstances. 



Sexuality and Temperature. — Temperature has a marked 

 influence on the sexes. A relatively high temperature favours 

 the corolla and androecium, while a comparatively lower 

 one the gynoecium. A. Knight long ago found that Water- 

 melons grown with a maximum of 110° by day, usually 

 varying from 90° to 105°, with a minimum of 70° at night, 

 grew with luxuriance, but bore no fruit, though it had a 

 profusion of minute male blossoms. This experience is 

 corroborated by present horticulturists. He was not sur- 

 prised, as he had for many years previously succeeded, by 

 long-continued low temperature, in making cucumber plants 

 produce female flowers only. 



Mr. Median's observations on the development of buds 

 on certain trees appeared to corroborate this view of 

 Knight's. He remarks that, in the year 1884, after a winter 

 of uniformly low temjieraturo, the male and female flow^ers 

 of the nut appeared together ; but in other years it was 



* Trans. Irish Acad., xxiv., p. 629; see also a paper ou " Sexuality," 

 by Dr. M. T. Masters, Pojj. Sci. Rev., xii., p. 3G3, 1873, and his Teratology, 

 p. 190; also, Proc. Acad. Nat. Sci. of Phil., 1873, p. 290. 



