Edith R. Saunders 221 



Dr D. H. Scott regarding a wood near Oakley (Hampshire), although 

 both forms were to be found in his garden about a mile away, here 

 however commercial seed had been introduced^ ; by other correspondents 

 in regard to the plants which occur abundantly on shingle in the neigh- 

 bourhood of Dungeness and in woods and coppices around Peasmarsh 

 (Sussex). 



These facts naturally give rise to the question as to when and where 

 the smooth-stemmed form first appeared. Did it arise spontaneously as 

 a wild plant or did it originate in cultivation and then become generally 

 distributed as a " garden escape." Or is the premise here involved not 

 really established and should we more properly enquire whether indeed 

 pubescens, as seems to be always assumed, or nudicaulis represents the 

 original type ? Whichever be the view adopted there remains to be con- 

 sidered the further question whether the one form arose from the other 

 by direct mutation, or as the result of hybridisation either with a hairy 

 species on the second supposition, or with a glabrous or partially glabrous 

 one on the first. If a direct mutation has taken place, then, according to 

 the accepted view we should have the case of a dominant mutant arising 

 from a recessive type. As a comparable case in another member of the 

 Scrophulareaceae we may cite Linaria alpina where the self-coloured 

 form concolor, though dominant, is regarded as a variety., the recessive 

 form with the orange patch on the lower lip as the type^ Here as in 

 Digitalis the two forms are distinguished by a solitary characteristic, in 

 every other respect they are identical. Such instances of mutation — if 

 mutation it be, and in Linaria there seems no ground for regarding it 

 otherwise — from a recessive to a dominant form, when only one factor 

 appears to be involved, are exceptional, and it is obvious that on the "pre- 

 sence and absence " theory of factors they present a certain difficulty. But 

 the alternative hypothesis which supposes that the smooth-stenimed Fox- 

 glove or the self-coloured Linaria is derived from a cross with another 

 species is also not free from difficulty. On this supposition we should 

 look in these forms for larger or smaller differences from the parent type 

 in a considerable number of characters such as are enumerated by Neilson 

 Jones^ as characterising his artificially raised (and hence authentic) 



1 I am indebted to Dr Scott for the f urtlier information that this was essentially an oak 

 and hazel wood, and that the soil was "clay with flints" resting upon qhalk. So far how- 

 ever the results of investigation do not seem to indicate that the appearance of nudicaulis 

 is conditioned by the character of the soil. 



2 See The Neio Phytologist, Vol. xi. 1912, p. 1G7. 



3 " Species Hybrids of Digitalis," J. of Genetics, Vol. ii. No. 2, 1912. 



