38 



DE. E. E. GATES— CONTEIBUTION TO A 



meant to give a better understanding of the differences between the more common 

 mutants and tbeir parent form, as well as their relationships to each other. It is clear 

 that the mutants differ from each other not in one but in many characters, and I am 



o 



reement with the conception of DeVries that all these characters are in each 



the expression of a single germinal change. 



But the appearance of so many so-called " combination types/' particularly in the 

 cultures of Schouten (1908), shows that all the characters do not necessarily remain 

 together under all circumstances. The " combination types " are supposed to originate 

 from the union of two germ-cells which have mutated in different directions, but the 

 significance and manner of origin of such types, and their relation to hybrid splitting, 

 will have to be determined by future investigations. If O. nanellaj for instance, is 

 capable of producing occasional types in its offspring such as O. nanella-oblonga, 

 O. nanella-elliptica^ 0. n.-lata, and O. n.-scinfillanSj then each of these leaf -types must be 

 potential or " latent " in O. nanella just as they are in O. LamarcViana^ and the only 

 quality really absent from O. nanella is stature. But " latent " is a dangerous word to 

 use, for it is only a cloak for ignorance regarding the real cause. It is possible, though 

 not probable, that some of the mutants from O. LamarcTciana appear only as alternative 

 dichogenous conditions which are environmentally determined very early in the 

 ontogeny. On the other hand, certain of them may be present in some germinal 

 condition resembling the heterozygous condition in Mendelian hybrids. But this 

 question and others relating to the interpretation of the mutation process are discussed 

 in another section. 



O. grandijiora^ Solander. 



The previous paragraphs dealt with O. Lamar cUana and its derivatives. A later 

 section will consider the derivatives from a naturalized colony of forms on the sand- 

 dunes of Lancashire which included both O. LamarcUana and O. grandijlora. The 

 latter species has already been carefully described (Vail, 1907) from plants derived from 

 the locahty in Tensaw, Alabama, where it still survives. It is frequently grown in 

 Botanical Gardens, and, particularly in Trance, it often goes under the name O. suaveo- 

 lens, Besf. I have grown cultures from the O. grandijlora naturalized in Lancashire, 

 and also from plants collected in the original locality in Alabama by Prof. S. M. Tracy. 

 I have already pointed out that this species formerly had a wide range in America, 

 extending eastwards to the Atlantic, where it long survived in Virginia and Carolma. 

 The eastern form probably differed in certain features from the Alabama form. 



In July, 1907, I began a greenhouse culture from seeds collected wild on the 

 Lancashire coast, for which I was indebted to Dr. D. T. MacDou<?al. The rosettes were 

 transplanted to individual pots when quite young, and they developed slowly and 

 perfectly under these conditions. About half of them were proved by their striking 

 rosette characters, and afterwards by their flowers, to belong to O. grandiflora, PI. 4. 

 fig. 45 shows one of these rosettes four months after germination, and PL 4. fig. 46 the 

 same type at the age of five and a half months. In the latter figure a new leaf-type has 

 appeared, with characteristic basal lobes, though the old type of leaf remains. This is 



