328 T. G. Hill and E. de Fraine. 
chinensis and Ephedra distachya, and spiral and pitted in Sciadopitys 
verticillata, etc. 1 
Fig. 11. P. lanceolata. Transverse section of cotyledon, shewing trans¬ 
fusion tracheides (t.t.) on the flanks and ventral side of the bundle, x 335. 
With regard to the function of the transfusion tracheides much 
cannot be said owing to the paucity of experimental data; it is, 
however, reasonable to suppose that they convey water from the 
vascular bundle to the surrounding mesophyll. At the same time 
they may be of value in storing water, a function which is suggested 
by their not infrequent isolated position, and they are thus com¬ 
parable to the barrel tracheides of certain Cactacese. 
The close resemblance in the structure and position of the 
transfusion tracheides of Persoonia and many Gymnosperms gives 
weight to the view 2 that in the latter plants the elements in question 
may have no connexion with centripetal wood, but are structures 
brought into being at the call of physiological necessity. 
Tuansition. 
The transition-phenomena exhibited by Persoonia lanceolata 
follow those of Van Tieghem’s Type 3, which is so well known that 
the briefest description only is required. 
In the plant in question each cotyledon normally has a single 
vascular bundle which usually remains endarch and collateral 
1 See Bernard, Daguillon, and Hill and de Fraine, loc. cit. 
2 See Carter: A Reconsideration of the Origin of Transfusion 
Tissue. Ann. Bot., 1911, XXV. 
