THE MUTATION THEORY 103 



"species" of the genus are really hybrids, and many of them breed 

 substantially true. I regard this constant presence of bad 

 pollen grains as an indication that the genetic physiology of 

 Oenothera is in some way abnormal, and as we shall presently 

 see, there are several other signs which point in the same direction. 



Discussion of the whole series of phenomena is rendered 

 exceedingly difficult first, by reason of the actual nature of the 

 material. The characteristics of many of the types which de Vries 

 has named are evasive. A few of these types, for instance, gigas, 

 nanella, albida, brevistylis, and perhaps a few more are evidently 

 clear enough, but we have as yet no figures and descriptions 

 precise enough to enable a reader to appreciate exactly the pe- 

 culiarities of the vast number of forms which have now to be 

 considered in any attempt to gain a comprehensive view of the 

 whole mass of facts. It is also not in dispute that the forms are 

 susceptible of great variations due simply to soil and cultural 

 influences. 



The fact that no Mendelian analysis has yet been found 

 applicable to this group of Oenotheras as a whole is perhaps largely 

 due to the fact that until recently such analysis has not been 

 seriously attempted. Following the system which he had 

 adopted before the rediscovery of Mendelism, or at all events, 

 before the development of that method of analysis, de Vries has 

 freely applied names to special combinations of characters and 

 has scarcely ever instituted a factorial analysis. Before we can 

 get much further this must be attempted. It may fail, but we 

 must know exactly where and how this failure comes about. 

 There are several indications that such a recognition of factorial 

 characters, could be carried some way. For example, the height, 

 the size of the flowers, the crinkling of the leaves, the brittleness 

 of the stems, perhaps even the red stripes on stems and fruits, 

 and many more, are all characters which may or may not depend 

 on distinct factors, but if such characters are really transmitted 

 in unresolved groups, the limitations of those groups should be 

 carefully determined. The free use of names for the several 

 forms, rather than for the characters, has greatly contributed 

 to deepen the obscurity which veils the whole subject. 



