66 Transactions. 



the vascular bundle, or running in rows from the lower to the 

 upper surface. The vascular bundle does not vary much except 

 in size. In the mature leaf there are lignified elements present 

 in the pericycle, but I have not ascertained their nature in this 

 species. They do not show any markings on their walls in 

 transverse section, but these may perhaps be seen in sections 

 •cut longitudinally. 



Dacrydium Kirkii. 



This species is very rare, and is confined to the north, where 

 only a very few trees occur. The material which has been used 

 was got by Professor Thomas, of this college, from a district 

 north of Auckland. I have none of the very early stages, all 

 investigation being confined to a single young plant, about 

 7 in. or 8 in. high, and to the foliage of the mature tree ; but 

 in this case the mature tree alone forms a very interesting study. 

 On the young plant there occurred only one land of leaf — one 

 like that of miro or totara, and in transverse section almost 

 identical ir shape and size to that of a totara-leaf. On the 

 mature tree we also find this kind of foliage, but longer and 

 broader. In addition to this large leaf, we find almost every 

 stage of reduction, to very small scale-like leaves, separate 

 from the stem only at their apices. On a single branch one 

 form may be seen gradually merging into the other, or we may 

 find quite abrupt changes. On this particular tree the larger 

 form predominated on the lower branches ; further up there 

 was a mixture of the two ; while on the top branches only scale 

 leaves were found. 



This example of dimorphic foliage in a Dacrydium forms 

 a great contrast to the example of P. dacrydioides. In the latter 

 we saw that dimorphic foliage only occurred on the younger 

 plants, whilst in the former it is found only on the mature. 

 That of kahikatea is an example of adaptation in the interme- 

 diate stages, the primitive form reinstating itself finally on the 

 mature tree. In Dacrydium Kirkii, however, the opposite is 

 the case, for here we have an example of adaptation late in life, 

 the adapted foliage being on the mature tree. The large, broad 

 lamina is well adapted in the early stages for vigorous growth, 

 but is evidently unsuitable in the mature state. 



We saw that in totara and miro the mature leaf was always 

 more reduced than those of the intermediate stages. Dacrydium 

 Kirkii has carried this reduction to the extreme. This extra- 

 ordinary amount of reduction, occurring in one and the same 

 mature tree, and accounting for the intermingling on one tree 

 of two totally distinct kinds of foliage, is perhaps not paralleled 

 by any other tree in existence. 



