68 Transactions. 



stages. This naturally follows, for the under surface is now 

 the more exposed. In the bundle we find a reduction of elements 

 corresponding to the reduction in size, but there are still large 

 groups of transfusion tracheids at the sides of the bundle. 



Transverse Section : Base tvhere Leaf has joined Stem. 



Stomata : We find no stomata now on the upper surface, 

 for the region in which they occurred has become joined to the 

 stem. The stomata are then, on the final stage, only on the 

 lower surface, and are here on the exposed surface ; but they 

 are greatly sunk, and are protected by the very close adpression 

 of the leaf to the stem, and by the overlapping of neighbouring 

 leaves. 



It is hardly necessary to give a summary of this leaf, the 

 description being scarcely more, but it may be as well to mention 

 again that — (1.) In Dacrydium Kirhii we have an example of 

 dimorphic foliage in a different genus to that of kahikatea. This 

 dimorphic foliage, however, occurs only on the old plants, while 

 in kahikatea it occurs only in the younger stages. The dimorphic 

 ioliage in D. Kirlii was a result of reduction from the more 

 primitive form ; that of kahikatea was the result of an enlarge- 

 ment of this form. (2.) In this leaf we have an example of 

 stomata preserved on both surfaces of a broad leaf to the mature 

 stage. Stomata at this stage were absent from the broad leaves 

 of totara, miro, and matai. The presence of these stomata. 

 and the absence of a sclerenchymatous hypoderm, makes it 

 possible to explain why a reduction has taken place in this 

 species. 



Comparison of Different Forms of Leaves. 



The species I have chosen represent very fairly the. different 

 types of foliage found in the New Zealand Podocarpece ; but, as 

 my thesis is already very extensive, I shall not be able to give 

 at present a comparison of these species with the other forms. 

 I should like to add, however, that the most common form of 

 leaf in the New Zealand Podocarpea' is that represented by 

 totara, miro, matai, and the earlier stages of Dacrydium Kirhii. 

 Of these species the totara-leaf represents the most advanced 

 form of this type, miro and Dacrydium Kirhii the simplest, 

 whilst matai is intermediate between the two. A comparison of 

 the structure in the " broad lamina " leaves of the Podocarpece, 

 in conjunction with their habitats, might lead to some very 

 interesting phytogenetic considerations. The totara is obviously 

 the best adapted for living in exposed positions, and it is 

 found where miro and matai could not survive. This type 

 of foliage, which, in many respects, corresponds to Tarns 



