SEXUALITY AND THE ENVIRONMENT. 245 



Summarizing the various influences of the environment 

 as climatic — such as temperature and light, shade and 

 obscurity, humidity and drought, a^; well as varieties of soil 

 and degrees of nourishment, and possibly others — we soon 

 see how careful one must be in attributing a result to any 

 one or special cause alone. What we can do is, as it were, 

 to pick out of them, as tolerably well-ascertained, condi- 

 tions which seem to favour, say, the female as compared with 

 the male organs or flowers — such as, e.g., a mean or optimum 

 condition of vegetative energy, a relatively low temperature, 

 no excess of nutriment, a due amount of light, humidity, 

 etc.; or again, on the other hand, a relatively higher tempera- 

 ture, which favours and stimulates the staminal energies, the 

 androecium being more keenly sensitive and more readily 

 responsive to slight increments of temperature than is the 

 gynoecium. The duration of the male elements being shorter 

 than that of the female, they can come more quickly to 

 maturity and perish earlier, as seen, for example, in the first 

 flowering deciduous male catkins of Castanea Americana 

 mentioned above. These, having been formed at the close 

 of the preceding year (like many male flowers of the 

 Umhelliferce late in the season), may represent the ex- 

 piring energy of the year's growth. They open first, as 

 soon as a sufficient though slight increment of temperature 

 occurs, but quickly fall off, quite useless, as no female 

 flowers are open to be benefited by them. 



Again, many, if not the majority of gjnodioecious plants 

 would seem to be produced by the first flowers opening 

 before the temperature was sufficiently high to allow of the 

 corolla and stamens to develop properly ; and though many 

 female flowers of the Lahiatce now blossom simultaneously 

 with the hermaphrodite flowers of the same species ; this 

 may be, perhaps, accounted for by hereditary influences, as 



