26 Transactions. 



seen only one specimen raised from Chilian seed,* and it resembles closely 

 the Chatham Island plant. S. microphylla and S. prostrata grow side by 

 side at the lower Waimakariri Gorge, Canterbury Plain. 



In the above case of Sophora the adult form is probably the stem form, 

 and the xerophytic divaricating shrub form an epharmonic adaptation 

 which arose during a probable period of drought on the east of the Southern 

 Alps at the time of the glacial period (see Diels. 1896, and Cockayne, 1900). 

 In certain parts of the problematical Greater New Zealand where the 

 climate still remained sufficiently wet the ancestral Sophora would re- 

 main unchanged ; so we still see S. grandiflora in the East Cape district 

 and S. tetraptera in the Auckland district and the Chatham Islands. In 

 the South Island there is only S. microphylla and S. prostrata, in the former 

 of which the xerophytic stimulus never evoked an absolutely hereditary 

 form, whereas in the latter the effect of the stimulus is much more deep- 

 seated. To what extent such a stimulus can leave its mark is shown in 

 the forest-tree Elaeocarpus Hookerianus, which at any age may put forth 

 reversion shoots high up the trunk or on the branches. The heteromorphy 

 in the other species listed above may be similarly explained. There is 

 first of all a short-lived erect mesophytic stage, then a long-persisting 

 xerophytic stage, and a final adult mesophytic stage. The first stage, 

 suited as it is to shelter by ground-plants, &c, is epharmonic ; it may 

 also be considered a survival from the ancestral plant. The second (xero- 

 phytic) stage was epharmonic during the steppe-climate period of the 

 eastern South Island, but is certainly beneficial no longer ;f and the adult 

 stage is more or less a return to the original form, but now called forth by 

 the present mesophytic conditions. According to this supposition, it is 

 considered that the tendency to both xerophytic and mesophytic form 

 is latent in the plant, and that one or the other will appear as soon as 

 the necessary intensity of stimulus is reached. Until that is the case, 

 whichever form is the more hereditary — i.e., the more strongly fixed — 

 will persist, even though it is far from being epharmonic. 



In a considerable number of instances there is a mesophytic juvenile 

 stage and a xerophytic adult. In this class the present mesophytic con- 

 ditions are not sufficient to inhibit the strongly hereditary xerophytic 

 form, which also in a number of cases is in harmony with the xerophytic 

 stations affected by these plants. The following examples of this and other 

 persistent juvenile forms may be noted : — > 



(1.) Shrubs which are leafy as juveniles, *but leafless as adults, when 

 they have flat or terete green assimilating stems — e.g., species of Car- 

 michaelia,% Notospartium, and Corallospartium. How unstable really is 

 the xerophily of many species of Carmichaelia is shown by their abundant 

 production of leaves in shady stations. 



(2.) Shrubs with an abundance of leaves, sometimes very thin, when 

 juvenile, but of the cupressoid form when adult — e.g., certain Taxaceae 

 (see Griff en, 1908), whipcord veronicas, and some species of Helichrysum 

 belonging to the section Ozothamnus. 



* The seed was very kindly sent to me by Dr. Eug. Autran, of Buenos Ayres, and 

 the seedlings were raised by Mr. T. W. Adams, to whom I am greatly indebted. 



t The divaricating form of Elaeocarpus Hookerianus and the juvenile Pseudopanax 

 crassifoliwm, with its thick, narrow, stiff, defiexed leaves, certainly seem out of place in 

 a rain forest, where they are assuredly not epharmonic structures. 



% Carmichaelia gracilis J. B. Armstrong is leafy in the adult ; it is a scrambling 

 iane, and grows in wet ground or swamps. C. grandiflora Hook. f. is deciduous, but 

 abundantly leafy in spring and summer. G. odorata Colenso is also leafy. 



