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 coiTespondents 

 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 propei-ly enquire whether indeed 

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

 original type i Whichever be the view adojjted 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-stemmed Fox- 

 glove or the self-coloured Linaria is derived fi-om 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 chai'acters such as are enumerated by Neilson 

 Jones^ as characterising his artificiallj' raised (and hence authentic) 



1 I am indebted to Dr Scott foi- the further information that this was essentially an oak 

 and hazel wood, and that the soil was "elay with flints'' resting upon chalk. 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. 



- See The New Phytologist, Vol. xi. 1912, p. 107. 



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



