566 LIFE : OUTLINES OF GENERAL BIOLOGY 



is a fundamental difference in physiological gearing. This initial 

 difference leads to the primary functional distinction between male 

 and female. But it also determines, either from the start, or after 

 maleness and femaleness have been established, what particular 

 expression will be given to a whole series of minor characters, both 

 structural and functional — whether a masculine or a feminine 

 expression. 



We must refer to the section on Sex-Determination for some of 

 the evidence in support of this view — that a deep, initial, constitu- 

 tional difference expresses itself primarily in what we may call 

 maleness or femaleness, and is also decisive, late or early, directly 

 or indirectly, in determining whether detailed characters will find 

 a masculine or a feminine expression. 



In some cases, probably, the initial 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 them- 

 selves 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 development of detailed 

 parts, and of habits as well as structure. In Vertebrate types this 

 activating of masculine or of feminine features is often under the 

 control of the hormones which are liberated into the blood from the 

 developing reproductive organs or gonads. 



It is important to realise the saturating influence of primary 

 maleness or femaleness, as the case may be. The sex-dimorphism is 

 pervasive, it goes through and through. As Havelock Ellis says, 

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

 down 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 throughout life — it is seen in the baby 

 boy and baby girl, it is expressed in old age. Of the more technical 

 evidence we give only one illustration. A castrated pullet may acquire 

 not only the outward structural features of the opposite sex — cock's 

 comb, wattles, long hackle and tail feathers, rapidly developing 

 spurs, carriage, etc., but the behaviour as well, even to the pug- 

 nacious character. 



It is also important to realise that masculinity and femininity 

 differ much in their accentuation. Thus, to recall but one instance, 

 the female of the Red-necked Phalarope is a perfect female, but 

 she is extraordinarily masculine; her mate is a perfect male, but 

 he is very feminine. 



The practical utility of this way of looking at things is obvious. 

 It suggests that the characteristic masculine and feminine features 

 are part and parcel of the normal man and woman, deeply rooted, 

 not tacked on, of ancient origin and therefore not likely to change 

 quickly. It suggests that they have a deep naturalness, and that 



