Gkiffin. — Development of New Zealand Conifer Leaves. 69 



■baccata, is supposed to represent the most primitive type 

 of Conifer leaf. The prevalence of this type in New Zealand 

 Conifers is very suggestive when we consider the complete 

 isolation of New Zealand from other countries, an isolation 

 which can only have taken place at a very early geological 

 period. 



Very different from the first type of foliage are the reduced 

 forms also found in the New Zealand Podocarpea?. The reduction 

 in Dacrydium Kirkii is a later development in its life-history, but 

 in rimu and kahikatea we find from the beginning of develop- 

 ment very much reduced forms. This reduction incites, both in 

 kahikatea and in rimu, an attempt, though very different in 

 each, to increase the surface for assimilation in the young plants. 

 It is very probable that this reduced form may have been 

 derived through scale leaves like those of the mature Dacrydium 

 Kirkii, but it is not within the scope of this thesis to go into 

 phytogenetic details regarding the origin of the different types of 

 Conifer foliage. 



It is hardly necessary here to draw any further conclusions 

 as regards the anatomical development in these species, as I 

 have given summaries and comparisons as I have proceeded. 

 My investigations have not been extensive enough to draw 

 many general conclusions for the whole group, but I should like 

 to show before concluding how far the development in these 

 species agrees with that of the Abietinece. For this purpose I 

 will give a very short summary and comparison on parallel lines 

 to that of M. Daguillon, which is quoted in the introduction 

 of this thesis. 



1. In the Podocarpeo3, as in the Abietinew, the existence of 

 leaves intermediate between the cotyledon and mature leaves 

 is constant. 



2. The passage from the primordial form in all species 

 investigated shows insensible transitions. We find nothing to 

 compare with Pinus, for though in the two plants with dimorphic 

 foliage— Podocarpus dacrydioides and Dacrydium Kirkii — we find 

 often abrupt changes, insensible transitional forms also occur. 



3. In the Podocarpeaj, as in the Abietinea?, the passage is 

 sometimes marked by a modification of phyllotaxis — e.g., 

 totara. 



4. Sometimes by a change in the epidermal surface. This 

 change is perhaps more marked in species of the Podocarpeae 

 than in the Abietinew. One or two parallel changes occur in 

 species of the two groups, especially as regards the position 

 of stomata. 



5. In both groups there is a development below the epiderm 

 of a sclerenchyrnatous hypoderm, though we find remarkable 



