348 Transactions. 



in damp stations in the South Island, and hereditary also in C. exsid, of 

 Lord Howe Island, the only species of the genus outside New Zealand. So 

 the presence of a scrambling form showing a tendency to twine in such a 

 rigid species as 0. subulata undoubtedly has close bearing on the question 

 of liana-evolution. 



Another interesting case is that of MueUenheclia complexa, already 

 noted, where, it may be remembered, the liane, having gained the upper- 

 most twigs of a dense shrub, shows a tendency to scramble rather than to 

 twine, interlacing branches, as pointed out, being more favourable for 

 scramblers than they are for twiners. 



In connection with such cases as the above we may note Darwin's 

 remarks : "As in many widely separated families of plants single species 

 and single genera possess the power of revolving, and have thus become 

 twiners, they must have independently acquired it, and cannot have 

 inherited it from a common progenitor. Hence I was led to predict that 

 some slight tendency to a movement of this kind would be found to be 

 far from uncommon with plants which did not climb, and that this had 

 afforded the basis for natural selection to work on and improve " (1878 

 p. 197). 



In any view of the development of twining the case of Antirrhinum 

 7naJHs is of interest. In a race of this well-known garden-plant a form has 

 been found which gives evidence of the inception of twining, the form 

 having, too, the characteristic anatomical features of twiners. It appears 

 to be a mutant, and it comes true to seed. 



The question next arises as to whether the tendency to twine has been 

 lost in certain plants. Darwin stated that this has happened in many 

 tendril-bearers, and in his observations on Clematis showed that the power 

 of twining was in this genus poor (1865, pp. 26-34). This point is brought 

 forward here on account of the behaviour of Clematis indivisa. 



In the section of this paper dealing with the methods of obtaining support 

 it has been stated that the developing seedlings of Clematis indivisa twine 

 round a thin support with which they come into contact ; but the seedlings, 

 being young, not one of those observed has made more than 5 spirals round 

 the support. However, the writer has found an older plant which has 

 attained a height of 2 m., the plant having made 14 spirals and still twining 

 regularly. Adult plants also are occasionally found which exhibit a slight 

 twining round their supports; but the twining in these cases is so slight 

 that it may possibly be due solely to irregular growth in the ascent of the 

 liane.* And we may notice here Calystegia Soldanella, a common inhabitant 

 of the sandy shore, where it forms a low compact mass (Cockayne, L., 

 1910, p. 67, fig. 27). This species has been seen by the writer at Day's Bay, 

 Wellington, growing in a sandy position where a number of low shrubs have 

 become established. Here numerous shoots of the Calystegia rise up among 

 the branches of the shrubs, and twine freely and regularly. Just as in 

 Clematis, it is probable that we have here a species whose ancestors were 

 twining-plants, and the capacity to twine, through inheritance from these, 

 lies latent in the plants which now occupy the exposed places of the sea- 

 shore. 



* Since this was written Dr. L. Cockaj^ne informs mc that he lias noted distinct 

 twining in a lar^e example of G. mdivisa in the forest on th(; southern slopes of Fount 

 Ruapehii. 



