Other Characters in Oenothera Lamarckiana. 469 



but are now generally regarded as visiljle manifestations 

 of a latent heritable potentiality. 



In the members of certain families, (which may be 

 large or small) the deviations in question become visil)le 

 so often, that the presumption in favor of a common 

 internal cause becomes very strong. On the other hand 

 the monstrous individuals are so frequently separated 

 from one another in pedigrees by perfectly normal ones 

 that the cause, if it is a continuous one, that is, if it is 

 handed on from one generation to another, must be in- 

 operative most of the time. Finally the appearance, or 

 non-appearance, of the monstrosity in particular individ- 

 uals is dependent on external influences and mainly on 

 nutritional conditions. This latter fact alone seems to 

 me sufficient to prove their presence, and consequently 

 their inheritance, in a latent state. 



Monstrosities are much more favorable material for 

 this purpose than mutations. For they are accessible to 

 everybody, and dependent for their appearance and de- 

 gree of development on their environment in ways which 

 are easily investigated. Except for hybrids, they afford 

 the best material for studying and elucidating the general 

 principles of latent characters. 



Monstrosities differ from mutations in that their ap- 

 pearance is partial : by this I mean that they do not affect 

 all the homologous organs of the same plant but only 

 some and usually very few of them; whereas the muta- 

 tions described in this part are absolutely individual. 

 Monstrosities need, by no means, be monstrous. The 

 appellation monstrosity is a very unfortunate one; be- 

 cause, in other species many of these teratological sports 

 are quite normal characters.^ As an example I might 



^ Monstmosites taxinomiques, as they are called by De Candolle. 



