358 Transactions. — Botany. 



which possibly may represent in some degree that of the 

 hypothetical ancestor. Thus a seedling plant of Veronica 

 armstrongii, Kirk, pot-bound, and so not subject to vigorous 

 growth, but kept in the mild and somewhat moist climate of 

 my greenhouse, still, although more than two years old and 

 12 cm. high, keeps in every part its seedling form, and may 

 very well indeed be a veritable reconstructed ancient type (see 

 Plates XXVIII. and XXIX.). The case cited above of Vero- 

 nica tetrasticha may be explained in a similar manner ; and 

 finally the leaves may also serve as organs for promotmg rapid 

 growth without upsetting the theory of reversion, since the 

 former ancestor, if provided with such leaves, and living under 

 ixiore favourable conditions, would certainly grow much faster 

 than its depauperated descendant. Also, quite a number of 

 plants never quite lose, or, at any rate, keep for a very long 

 lime, these seedling forms, which exist side by side under 

 the same conditions with the mature, sometimes even on 

 the same shoot. Parsonsia (all the species), Dacrydium (all 

 the species), Muhlenbeckia complcxa and M. adpressa, Goya 

 tyallii, and Hoheria angustifolia afford good examples, while 

 Pscndo])anax is more remarkable still, smce it goes through 

 at least three different forms, and does not assume the 

 last form — most distinct from the preceding, but which is 

 not much unlike the early leaves — until quite late in life. 



That such great instability of species should occur in our 

 flora is not to be wondered at when we consider • — with 

 Captain Hutton and those later writers who have follow^ed 

 his theories — the diverse origin of our flora, and the com- 

 paratively recent great changes which have taken place since 

 all our plant immigrants finally settled down in their island 

 home. This insular habitat, as pointed out by Diels, would, 

 when a change in climate came, cause the survival afterwards 

 of various ancient forms in stations not suitable for their 

 well-being," whereas in a continent they would under similar 

 circumstances either migrate to a suitable spot or be wiped 

 out by forms better suited to the new conditions. In such 

 an unfavourable locality these survivors would, I may venture 

 to suggest, be modified more or less in outward appearance, 

 but W'Ould never become really stable species. A good case 

 in point is Baoulia hryoides and Raoulia viammillaris, both 

 of which, under cultivation in a greenhouse, develope true 

 leaves, and become in habit much more like their relatives of 



* Carmichalia crassicaule, Raoulia mammillaris, R. eximia, R. 

 hryoides, Haastia pulvinaris, H. rcciova, H. sinclairii, most inhabitants 

 of shingle-slips, Veronica (of the whip-cord and epacridea type), V. 

 bttxifolia, Ozotliamnus, Panax lincarc, Notospartium, Epilohium crassicm, 

 Hymcnanthera alpina, Carviichalia monroi, C. rohusta (?), Senecio cas- 

 sinioides, &c., are probably examples of such forms. 



