WHAT IS THE ORIGIN OF SPECIES? 18$ 



is simply an assemblage of individuals which agree with one 

 another, and differ from the rest of the living world in the 

 sum of their morphological characters;" and further, "in 

 the physiological sense, a species means, firstly, a group of 

 animals the members of which are capable of completely fer- 

 tile union with one another, but not with the members of any 

 other group; and, secondly, it means all the descendants of 

 a primitive ancestor, or ancestors, supposed to have originated 

 otherwise than by ordinary generation."* 



Meaning of "Origin of Species." What, then, do we really 

 mean -when we ask, What is the origin of species? It is 

 not the sum of morphological characters, which Huxley says 

 does not exist, but the morphological characters themselves, 

 which concern us. It is not the assemblage of individuals 

 which agree or differ one from another, or the group of ani- 

 mals which have certain capabilities and have certain com- 

 mon ancestors, whose origin we are seeking ; it is the origin of 

 those differences and agreements in morphological characters 

 which are the marks of the morphological species, and of the 

 capabilities and disabilities which constitute the characteristics 

 of the physiological species, that is meant by the phrase * ' ori- 

 gin of species.'" 



Development of Individual Characters Known and Observed. 

 The naturalist is familiar with the development of the indi- 

 vidual ; he knows very well that the adult differs by well- 

 marked morphological characters from the infant, and more so 

 from the embryo; and he further knows that the stages of 

 development are brought about by successive minute changes 

 of form. The difference existing between the gamecock, 

 with its complex physical organization and high qualities 

 of courage, skill, and determination, shown while fighting its 

 fellow to the death, and the motionless and apparently homo- 

 geneous yolk suspended in its bed of albumen, are differ 

 ences brought about by the processes of ontogenesis in a very 

 short space of time. 



The Law of Development. The origin of the individual or- 

 ganism with all its complexity, both morphological and phys- 



* Loc. cit., pp. 242, 291, 296. 



