412 



TRANSMISSION 



resident within the germ, from which they slowly disappear 

 when no longer favored by the conditions of life and no longer 

 sustained by selection. These vital units, if ever discovered, will 

 be found to be closely connected with the origin of characters 

 as well as with their preservation. 



We shall see later that, when a character is undergoing rigor- 

 ous selection new and higher values than ever before are constantly 

 appearing. May not the reverse be also true, namely, that a 

 character on the decline may present its successive decreasing 

 values because of influences entirely internal ? 



That disappearance of parts is not due entirely to disuse is 

 shown by the fact that the process continues long after the fact 

 of disuse could have the slightest influence. Where a rudi- 

 mentary tibia further degenerates to a rudimentary pelvic bone, 

 the question of disuse is certainly not involved ; neither is use 

 or disuse involved in breeding for high or low oil in corn, for 

 example. Manifestly some biological principle is involved that 

 has not yet been discovered and identified, and, as it is evidently 

 a principle fundamental to transmission and variation, its isola- 

 tion is exceedingly important. 



Characters not dependent upon adaptation. Generally speak- 

 ing, there is a close correlation between the development of a 

 character and its usefulness to the individual and the species. 1 

 This fact has given rise to the impression that all characters 

 are dependent upon teleological principles for their existence. 

 No greater error could be made. It is true that in nature selec- 

 tion operates mostly along utilitarian lines, and in this way after 

 a time it brings most characters into line with the greatest 

 service and the closest adaptation; but selection may operate in 

 any direction, even to the disadvantage of a species. In this 

 case, however, the response is to selection, not to utility. 



Neither is development along utilitarian lines necessarily 

 true of those characters that lie outside the field of selection 

 or of those upon which it operates too rarely to impress itself. 

 For example, the instinct to fly toward a source of light 

 would exterminate certain species if naked fire were more gener- 

 ally encountered. That the testicle in mammals should have 



1 Known among biologists as teleology. 



