8 Transactions. 



IV. Mutations.* 



There seems to be no doubt but that De Vriesian mutations arise from 

 time to time. That such afford a better material for preservation by natural 

 selection than do small fluctuating variations is obvious. Unfortunately, 

 the number of cases of veritable mutants is small, while most have originated 

 in cultivation. This last fact discounts the value of the mutation theory 

 in the opinion of many.f My own feeling, as an amateur gardener of many 

 years' standing, and as one who has cultivated with his own hands several 

 thousand species of both wild and garden plants in an antipodean garden 

 far from the home of most, is that ordinary cultivation, without manure, 

 has little effect in producing variations of moment. In my garden, plants 

 reproduced themselves from seed freely and came to maturity, but beyond 

 a number of daffodils and some, probably hybrid, dwarf phloxes (Phlox 

 subulata L.) I remember nothing " new." 



In estimating the origin of species by mutation, nothing but experi- 

 ment can prove the heredity of the new character. All that ecology can 

 do is to note striking varieties, their frequency, their environment, the 

 position of the individual possessing such variations with regard to normal 

 individuals, and so on. 



The following examples of what may be full or partial mutations in 

 the New Zealand flora, indigenous and introduced, may be of interest : — 



1. The white form of Myosotidium nobile Hook. 



The species is confined to the Chatham Islands, where it grows on or 

 near the sea-shore. In the normal form the central half of the corolla is 

 bright blue, which fades to purple, and the edges are more or less white. 

 Mrs. Chudleigh, of Wharekauri, some years ago discovered one plant with 

 white flowers growing wild in the north of the main island, and although she 

 is an excellent observer, and Myosotidium: has been carefully noted in its 

 habitat by Mr. Cox and others, no more white-flowered forms have been 

 observed. The plant in question is now fairly common in cultivation, and. I 

 understand, comes true from seed. So, too, does the normal blue form. J 



* Something not very different to the mutation theory was propounded by J. B. 

 Armstrong, formerly of the Christchurch Botanical Garden, in a paper dealing with the 

 New Zealand species of Veronica in 1881, in these words : " I have been enabled to observe 

 numerous garden-seedlings of many of the forms, and they almost invariably resemble 

 their parents. Sometimes, however, sports appear, and when this happens there seems 

 to be a strong tendency on the part of the sport to reproduce itself, and it appears to 

 me that it is just in this manner that the greater number of our native forms have been 

 produced. At some very distant date there were probably only two or three (perhaps only 

 one) species existing within the limits of the colony ; but, oir account of the extreme 

 local variations of climate and varied geological formation of the surface, certain varia- 

 tions occurred, and a sport so produced, being self-fertile, and having within itself all 

 the elements required for reproduction, naturally reproduced its like until another such 

 sport occurred, and thus the forms gradually became differentiated from the type, and 

 by a long series of such sports one large family of Veronicas has been formed." Then 

 he goes on to show how similar mutations have taken places amongst species of other 

 lands, and considers that the intermediates have been eradicated " by man or the larger 

 animals, leaving only in most cases the more widely differentiated forms." But in 

 New Zealand man has done little, and very many intermediate forms have been pre- 

 served. 



f Klebs, however, writes (1910, p. 241), " Even if it is demonstrated that he was 

 simply dealing with the splitting-up of a hybrid, the facts adduced in no sense lose their 

 very great value." 



% Raising from seed is, in fact, the only satisfactory method of propagating both 

 the type and the white-flowered form. 



