Introduction; Variation. 
69 
with Beddard’s theory, the reduction in size and the quiet disposition of the 
male bird should be due to the partial atrophy of the male organs. B^ddard s 
theory here seems to contain the most probable explanation, and it would be 
well to make observations on other Centropodinae. It still remains to be demon- 
strated how such an aberration has arisen, which is perhaps comparable o e 
development of only the left ovary') in the female of all birds. 
In the case of Turnia; nigricollis, in which the male does most of the work o 
incubatins: the eggs, the large and strikingly coloured female is supposed lo 
observatiom by Mr. Krohn (Gefied. Welt, 1894, 190) to be given to polyandry. 
Darwin cites Jerdon’s remark that the females are “much more common y 
met Avith than the males”. It is difficult to reconcile this statement AAit 
former supposition, but these cases are mentioned here as showing t at ^ 
contrast in size, habits, etc., may sometimes, as in Centrococcyx, he accompanie , 
and perhaps determined, by a deficiency of reproductive eneigy or capacity, or 
sometimes, as perhaps in Turnix, by an excess of reproductive poAvei. 
In addition to the 6 theories of the origin of secondary sexua c arac eis 
mentioned above at least two more can be indicated. „ ^ , -irr 1 1 
7. Secondary sexual characters as “recognition markings . r. a 
(Darwinism, 1889, p. 217 et scq., and in other works) seems to have een e 
first to define conspicuous markings and patches of colour as use u mean y 
which individuals of a species may at once recognise others o t eir oAvn 
He applies his theory to species and further on tp. 284) to the sexes. 
8. Development of accessory sexual characters OAving to ex er 
violence or excessive physiological employment of the parts in question. 
Use promotes the development of a part in the individual, disuse its atrop y. li- 
the next section of this chapter reason is also given for the opinion that inuti ations 
of feathers - and hence of other parts - if repeated for generations are inherited. 
In the present case out of 8 theories of the origin of seco^ndary 
characters it may well be that G have been actually operatiAe in Is atm e, 
ing alone or more likely in different combinations and def,rees. 
causes are: 
1 . The differences of the reproductive organs (Theory b). 
2. Higher development OAving to a prepotency of growth-foice ( y 
3. Survival of the fittest in combat (Theory 2). p,,fernal 
4. The stimulation of parts to a higher development by use and 
violence or irritation (Theory 8). aud nre- 
5. Development of aleT I " - 
ferential mating of males and lemaies wn 
0.’) CttavfeoZtion for the sex which broods on the eggs (Theory 4). 
') 
A rudimentary 
As to Darwin 
11 (fi-adow Voff. in Bronn’s Kl. u. Ord. 
itrlit ovary is usually present (Craaow, vo„. 
“theory of sexual selection authors are disagreed. 
1891, p. 842;. 
