No. 633] H 



THE OSTRICH 



297 



The African wart-hog (Phaendurrus) has the peculiar habit of kneel- 

 and pushes itself forward with its himl-limbs. It ha> Mn.n.ir horny 

 even in the embryos. This seems to some naturalists to be a satisfactory 

 an instance of an adaptive peculiarity of germinal origin wrought out by 



In the latter part of the above quotation Thomson 

 merely presents the two opposing views without afford- 

 ing us the advantage of his own. The last sentence is a 

 succinct expression of present-day orthodoxy, and we 

 may well consider how far it is justifiable in the case of 

 the ostrich. It is manifest that from their very nature 

 the callosities are outside the realm of competitive strife, 

 and therefore could not have been "wrought out by 

 natural selection." If a character is such that it must 

 perforce be produced as a result of the every-day activi- 

 ties of an animal it is as wholly gratuitous to invoke 

 natural selection as it would be to seek an independent 

 germinal origin. As already shown, the skin of the 

 ostrich is of such a nature that it will form callosities 

 wherever friction and pressure are intermittently ap- 

 plied, just as surely as they will be produced on the 

 human hand as a result of manual labor, on the finger 

 tips of the harpist, violinist or rosary devotee, or on toes 

 encased in ill-fitting boots, with all of which natural selec- 

 tion has no concern. Originally natural selection may 

 have been operative in the survival of animals hav- 

 ing the inherent power to form the thickenings, but we 

 have abundant evidence that all the higher forms now 

 possess it. 



When the ancestral ostrich first took to resting on 

 its sternum and pubis and rocking from side to side, the 

 callous thickenings would arise quite apart from any 

 antecedent formation and whether or not the germ-plasm 

 had anticipated the need. An inherent power is trans- 

 mitted, and nothing is gained by transmitting the cal- 

 losities themselves, since they are adaptations which 

 could arise in the natural course as needed. Xo selection 



