94 THE EVOLUTION OF LIVING BEINGS. 



ra Hieracium and Antennaria, though occasionally 

 able to reproduce themselves in the normal sexual way, 

 and consequently open to an occasional cross, yet 

 usually, behave Uke Taraxum which explains their high 

 degree of polymorphism. 



Of course, if apogamy follows directly upon a cross, 

 it perpetuates not only the homozygous forms but the 

 heterozygous ones as well — just as cuttings do — so 

 that the conclusion, drawn by East and Hayes from 

 the fact (if it be a fact) that such Hieracia occasionally 

 „vary" and consequently crossing can not be the only 

 cause of „ variabiUty", is unwarranted because of course 

 heterozygous apogamous forms can give rise to a num- 

 ber of different forms, can „vary" as a result of vegeta- 

 tive segregation, shown by East himself, to exist f . i. 

 among potatoes. 



Summa Summarum, I think we may say that a Lin- 

 neon is a vestigial group of a once much larger group of 

 differently constituted types, horn from a cross, which is 

 apt to simulate a species by the overwhelming majority of 

 the dominant types it contains, as a result of free-inter- 

 crossing, combined with a favoring of the dominants by a 

 process of selection, weeding out the weaker or more con- 

 spicuous recessives; this uniformity being more apparent 

 than real, because pure dominants are indistinctible, in 

 m^st cases, from dominant-hybrids. 



A Linneon consequently is nothing but a group of 

 morphologically similar individuals. It may consist of 

 almost nothing but pure species and a few hybrids, as 

 it does in habitual self-fertilizers ; it may consist of a 

 mixture of homozygotes and heterozygotes, reprodu- 



