356 Transactions. — Botanv. 



important facts, while from the differences between the earlier 

 and later developed leaves, and the younger and older forms 

 of the plant, much information as to the phylogeny of a 

 species or of an organ may be afforded. In his recent work, 

 " A Text-book of Botany," Strasburger says (page 46), " A 

 highly organized plant which begins its development with the 

 simplest stages and gradually advances to a higher state of 

 differentiation repeats in its ontogeny its phylogenetic develop- 

 ment " ; and further on, " From the fossil remains of former 

 geological periods it is safe to conclude that such Conifers as 

 Thuja, Biota, and the various Jumpers that now have scale- 

 like compressed leaves have been derived from Conifers with 

 needle-shaped leaves. This conclusion is further confirmed 

 by the fact that on the young plants of the scaly Conifers 

 typical needle-shaped leaves are at first developed. The 

 modified leaf-form does not make its appearance until the 

 young plant has attained a certain age, while in some Junipers 

 needle-shaped leaves are retained throughout their whole 

 existence." Reference is also made to the Australian Acacias, 

 whose early pinnate leaves in many cases become eventually 

 phyllodes, and he concludes with these words : " That it is 

 permissible on such phylogenetic grounds to conclude that 

 the Australian Acacias have lost then- leaf-blades in compara- 

 tively recent times, and have in their stead developed the 

 much more resistant phyllodes as being better adapted to 

 withstand the Australian climate. The appearance accord- 

 ingly of the phyllodes at so late a stage in the ontogenetic 

 development of the Acacias is in conformity with their recent 

 origin." 



In a similar manner, Sir John Lubbock argnes (" Flowers, 

 Fruits, and Leaves," page 141) " that the present furze is 

 descended from ancestors with trifoliate leaves" ; and further 

 on he explains by an examination of seedling conditions how 

 lobed leaves are of more recent origin than cordate leaves. 



Besides the above-quoted instances, many others could be 

 cited from foreign plants,-'' but in no flora in the world is this 

 phenomenon of such common occurrence as in the flora of 

 New Zealand.! Indeed, it will be seen from subsequent parts 

 of this inquiry that a very large percentage of our plants 

 exhibit most startling phenomena of this kind. And it is not 



* See " Aspects of the Phsenogamic Vegetation of Rodriguez," by 

 J. Bayley Balfour, D.Sc, F.L.S., in Journ. Linn. Soc. (Botany), vol. xvi., 

 pp. 7-25. 



t On this point I can speak with some authority, since during the 

 past few years I have personally raised from seed several thousands of 

 species of extra-tropical plants, and in few, save certain Australian 

 genera and Conifers, have I noticed any marked changes in leaf-form to 

 lake place. 



