76 ORGANIC EVOLUTION — THE FACTORS 



less "fit" rivals. A race with thick and solid frontal bones 

 would thus have been estabUshed, and it is not difficult 

 to understand how, by the same process of evolution, 

 those portions of the frontal bones which most received 

 the impact of blows, and were most employed to injure 

 rivals, thickened and solidified most (not by the accu- 

 mulation of acquired variations, but solely by the ac- 

 cumulation of inborn variations, by the survival of the 

 fittest), till there gradually appeared excrescences, which, 

 by the continual survival of the more and more " fit," 

 grew larger in each successive generation, till at last 

 the evolution of horns was completed. That the horns 

 of deer are two in number and symmetrical does not 

 affect the question, for a single horn has been evolved 

 in both the rhinoceros and the narwhale, and in the 

 latter the horn is asjanmetrical. Moreover, a fatal 

 objection to Mr. Cunninghame's theory is the fact 

 that horns do not grow under direct stimulation, that 

 of use. It may be that they grow in response to some 

 form of indirect stimulation (sexual emotion), and that 

 they would not develop in an imperfect animal, but I 

 am unable to vouch for this. The essential point is 

 that during growth the horns, being covered by tender 

 " velvet," are carefully protected by the animal from 

 injury, and it is not until the velvet is dead and has 

 peeled away, and growth has ceased, that the animal 

 engages in combat. Use therefore can have had nothing 

 to do Avitli the development of horns. 



In the case of Avorker bees it is impossible that evolu- 

 tion can have proceeded on lines of acquired variations, 

 for the simple reason that since workers have no descend- 

 ants they cannot transmit any variation acquired or 

 inborn. Their evolution must therefore have resulted 

 from variations in the successive ancestral queens of 

 such a nature as caused them to produce in the course 

 of generations better and better workers ; those queens 



