138 THE BIOLOGY OF THE SEASONS 



male or female lines of development determines sooner 

 or later, whether the detailed characters take a masculine 

 or a feminine expression. In some cases, probably, the 

 initial constitutional difference is itself continued on in 

 the building up of every part, deciding, as it were, at 

 point after point, whether the hereditary characters 

 will express themselves in the masculine or in the 

 feminine mode. In other cases, certainly, it is the 

 saturating influence of the early established maleness or 

 femaleness that determines the masculine or feminine 

 development of detailed parts, and of habits as well as 

 structure. 



What is the nature of the evidence that might be adduced 

 to illustrate the saturating influence of the primary male- 

 ness or femaleness, as the case may be? It is indirect 

 rather than demonstrative. The sex-dimorphism is per- 

 vasive, it goes through and through. As Havelock Ellis 

 says : "A man is a man to his very thumbs, and a woman 

 a woman to her little toes." The difference can be read 

 in the blood so safe and subtle an index to what goes on 

 throughout the body. The difference can be read thrpugh- 

 out life it is seen, for instance, in the baby boy and baby 

 girl, it is expressed in old age. It is seen even in the 

 different ways in which the two sexes take the same disease. 



Of more technical evidence we give only one illustration. 

 A spae'd pullet may acquire not only the outward struc- 

 tural features of the opposite sex cock's comb, wattles, 

 long hackle and tail feathers, rapidly developing spurs, 

 carriage, etc., but the behaviour as well, and the pugnacious 

 disposition ! 



It is very important, we think, to realise that masculinity 

 and femininity differ greatly in their accentuation. There 

 is no such contrast in the sexes of starfish, but it is 

 obtrusive in turkeys. And just as there are individual 



