THE EVOLUTION OF LIVING BEINGS. 83 



,,bezw. kahle Individuen ab; auch nach sorgfaltig- 

 ,,ster Reinpfliickung erha.lt man somit das nachste Jahr 

 ,,wieder dieselben Abweichungen, obwohl eventuell in 

 ,,geringerer Zahl." 



In cases where crossing is entirely excluded, the 

 only selection possible is through extermination of cer- 

 tain species within the Linneon. That, although strict 

 fertilizers may not exist, at least some forms cross 

 much less frequently than others, results from Nilsson- 

 Ehle's experience in a mixed planting of Pudelweizen 

 and a wheat designated as n. 0728, which showed 

 that the first kind was spontaneously crossed by the 

 latter, but the latter not by the first. 



Yet, so great a selfprotection against crossing is rare 

 in nature. 



So that, if our contention is correct,that a Linneon is 

 a group of individuals of dif ferentconstitutions, which is 

 but a rest of many more different types which sprang 

 from a cross, andif selection causes a freely intercrossing 

 community in nature to become apparently uniform 

 in aspect, we may expect to find that, especially 

 among animals, the Linneons will, by their uniform 

 aspect, tend to simulate species. 



This question is of such considerable importance, 

 and touches so closely the question how one came to 

 consider the appearance of individuals, deviating from 

 the form, considered to be typical for a particular 

 Linneon, as evidence of variability, that I may be 

 permitted to enlarge a little upon it. 



Let us take as an example the wild rabbits, refer- 

 red to the Linneon : Lepus cuniculus. 



