False Atavism 189 



types are themselves quite stable, or when it is 

 not at all intended to raise the question of their 

 stability. In scientific works it is commonly 

 used to designate the occurrence of subspecies 

 or varieties, and the same is the case in the 

 ordinary use of the term when dealing with 

 cultivated plants. A species may consist of 

 larger or smaller groups of such units, and 

 they may be absolutely constant, never sport- 

 ing if hybridization is precluded, and neverthe- 

 less it may be called highly variable. The 

 opium-poppy affords a good instance. It 

 ^' varies " in height, in color of foliage and 

 flowers ; the last are often double or laciniated ; 

 it may have white or bluish seeds, the capsules 

 may open themselves or remain closed and so 

 on. But every single variety is absolutely con- 

 stant, and never runs into another, when the 

 flowers are artificial!}' pollinated and the visits 

 of insects excluded. So it is with many other 

 species. They are at the same time wholly 

 stable and very variable. 



The terms variation and varietv are used 

 frequently when speaking of hybrids. By cross- 

 ing forms, which are already variable in the 

 sense just mentioned, it is easy to multiply the 

 number of the types, and even in crossing pure 

 forms the different characters mav be combined 

 in different ways, the resulting combinations 



