28 THE ORGANIC GROWTH OF THE LIVING WORLD sec. 



Wall-lizard," also in the addresses " On the Markings of 

 Birds and Mammals," and " On the Conception of the Animal 

 Individual," and have shown principally — 



1. That the progressive evolution of a character in a definite 

 direction — let us take as an example the origin of beautiful 

 ocelli on the skin of an animal ^ — exhibits perfectly regular 

 stages. In the case referred to we have (a) longitudinal 

 striping, (6) black spots, (c) formation of black rings, ((^) the 

 appearance of the coloured nucleus. These stages succeed 

 one another during the growth of the animal. In other words 

 the whole series of modifications is repeated in the develop- 

 ment of every individual. 



2. That where new characters appear, the males, and indeed 

 the vigorous old males, acquire them first, that the females on 

 the contrary remain always at a more juvenile lower stage, 

 and that the males transmit these new characters to the 

 species. (Law of male preponderance.) 



3. That the appearance of new characters always takes 

 place at definite parts of the body, usually the posterior end, 

 and during development — with age — passes forwards, while 

 still newer characters follow after from behind. Thus durinsj 

 life, e.g. in lizards, a series of markings pass in succession over 

 the body from behind forwards, just as one wave follows 

 another, and the anterior ones vanish while new ones 



^ I have here iu my mind an example which by no means serves for all cases. 

 It is to he understood that it is not at all essential that I should mention the 

 origin of ocelli rather than of other characters. Of course all, even the most 

 splendid, ocelli can be proved to arise from the simplest markings, the simplest 

 spots. (Compare my remarks on this j^oint at the Berlin Naturalists' Congress, 

 1886, in the published reports of that Congress, and also especially my observa- 

 tions on butterflies now in course of publication.) That the gradual development 

 can be demonstrated even on the feathers of one and the same adult bird has been 

 already sho^vn by Darwin for the Argus-pheasant. Herr Stud. Kerschner de- 

 monstrated very beautifully the same thing in the peacock, showing in accordance 

 with my theory how in that particular case the development can be followed 

 gradually step by step in definite parts of the body. (Compare his paper in the 

 Zeitschr.f. WissenchaftL ZooL, 1886.) Unfortunately he has in other respects 

 almost completely misunderstood the laws established by me. 



