Germ-Tracks and Somatic Tracks 91 



modified above, seems to me to be of prime importance. 

 While natural selection appears to act upon the qualities 

 of the finished organism, in reality it acts upon the bearers 

 of these characters hidden in the germ-cells.^ This im- 

 portant law has been raised above all doubt by the ex- 

 periences of animal and plant-breeders. Vilmorin, in his 

 breeding experiments, distinguished the individuals which 

 possessed in a higher degree the power of transmitting 

 their visible qualities to their descendants from those that 

 possessed it to a lesser degree.^ The former he called 

 hons etalons, and those he selected for breeding. But 

 whether a plant belonged to this privileged group the plant 

 itself did not show. This had to be decided by the de- 

 scendants and by these was the great breeder guided in 

 the selection of his breeding plants. 



The body of the individual, therefore, gives only a 

 one-sided and very incomplete indication of the qualities 

 represented in its germ-tracks. But when one grows 

 from its seeds hundreds and thousands of specimens, these 

 furnish such a many-sided picture that the average may 

 be regarded as a criterion of those latent attributes. 



By far the most of the hereditary character-units at- 

 tain their development only in the somatic paths ; it is only 

 here that the corresponding characters of the organism 

 become visible to us. But the transmission of a char- 

 acter and its development are, as Darwin says,^*^ distinct 

 powers which need not necessarily run parallel. The 

 transmission is accomplished invisibly, in the germ-tracks, 



sWeismann, A. Ucber die Vererbung. p. 56. 



^Vilmorin, L. L. de. Notices siir I' amelioration des plantes par 

 le semis. Nouvelle Edition, p. 44. 1886. 



loDarwin, C. The Variation of Animals and Plants. 2: 38. New 

 York, 1900. 



