50 Transactions. 



In the cotyledon, a sclerenchymatous hypoderni at the 

 margins, and at a later stage one or two isolated elements along 

 the sides ; stomata on both surfaces ; highly differentiated 

 parenchyma cells, and two vascular bundles, with tannin-sacs, 

 but no resin-canal ; very few transfusion tracheids, and a great 

 number of crushed protophloem elements. Near the apex of 

 the cotyledon we find, less wood in bundle and more transfusion 

 tracheids at sides, while in the older cotyledon we see a tend- 

 ency for the bundles to divide up again. 



In leaves of the same plant, hypoderm elements along sides ; 

 stomata deeply sunk only on under - surface ; one vascular 

 bundle, with a resin-canal ; and a greater number of trans- 

 fusion tracheids and less crushed protophloem. 



In later stages, fully developed sclerenchymatous hypo- 

 derm ; greatly modified accessory transfusion tissue, with pits 

 and lignified walls. 



In shrub and mature stages, the same characters in the trans- 

 fusion tissue ; greater development of chlorophyll parenchyma, 

 both of palisade and irregular- shaped cells. In the shrub, leaves 

 standing out at right angles ; in the mature tree, more parallel 

 to stem. 



In all stages we see a gradual increase in the number of 

 transfusion tracheids from the early stages to the later. 



The development, then, of P. totara is chiefly marked by 

 the acquisition of protective characters and by the production 

 of increased facilities for conduction, especially of water, both 

 in the bundle itself and towards the margins. The mature 

 form does not differ greatly from the leaf of the first year, and 

 shows many points of resemblance even with the cotyledon. 



Origin of Transfusion Tissue. • 



Now, from the cotyledon up to the mature leaf there appears 

 in every stage undoubted transfusion tracheids. These I have 

 verified not only by double stained transverse sections, but 

 also by longitudinal sections, both radial and tangential. 



Mr. Worsdell, in his paper on " Transfusion Tissue," says, 

 concerning Podocarpus totara. — " In the much shorter and 

 narrower leaf of this species it is interesting to note the complete 

 absence of this tissue [i.e., transfusion] in the leaf. Here the 

 central mesophyll cells are elongated in the direction of the 

 margin of the leaf, but are thin- walled and unpitted. I was 

 able to determine, however, the presence of a very slight ligni- 

 fication of their walls." These remarks are directly opposed 

 to what the present writer has found in the leaves of this species. 

 I do not know what material Mr. Worsdell had at his disposal, 

 or what methods he used in obtaining his results, but with 



