22 Proceedings of the Royal Irish Academy. 



distinct, short, triangular lobes, entire or with one or two teeth ; base triuicate, 

 with a euneate central part ; main nerves arising at the junction of the 

 petiole with the euneate part of the blade ; glabrous except for a tuft of hairs 

 at the origin of the nerves. Fruit-balls, three on the peduncle, small, about 

 J inch in diameter, composed of relatively few imperfect achenes, in which 

 no embryos are present ; acheue dome-shaped, flatter than in P. oriendxlis, 

 which it otherwise resembles. 



This rare tree resembles P. occidental is in the form of the leaves, except 

 as regards the peculiarly nerved euneate base ; but the fruit sc^ircely differs 

 from that of P. iiri>n(i(lis. It is like one of the two seetUings of P. acerijolia 

 which were raised at Cambridge and are now at Glasuevin, and may be of 

 similar origin. 



9. Platanus parviloba. .V. Henry, Hijbritla nora. 



A grafted tree at Kew, of unkm-wu origin and witliout a label, devoid of 

 the vigour of /'. urerifolia. I>eaves varialile ; the larger terminal ones, about 

 6 inches bnuid, with five short slightly dentate oblong-triangular lobes, and a 

 truncate liase, with the main nerves arising at the junction of the petiole 

 with the blade ; smaller leaves with three entire triangular lobes and a 

 rounded base, the fourth and fifth lobes being represented by a tooth ; 

 tomentum persistent ai tlie l>ase of the nerve and on the })eliole. Fruit-balls, 

 3-6, small, about J inch in diamelvr, made up of relatively few achenes, some 

 of which are imperfect, while othei-s contain an embryo. Achene with 

 touientosti Ixnly ami conical nearly glabrous head ; style often breaking off 

 neur its insertion. 



This )N3culiar iree, while closely resembling the London Plane, is clearly 

 distinct, and is probably a seedling of the second generation. 



Vtin-iilfti. — An attempt was made to discover the ages of the different 

 hybrid planes by nieasuring the " vein-islets" of their leaves. H. M. Benedict, in 

 a study' of the senile changes which occur in the wild vine, Vitis vulpina, found 

 the relative proportion of the soft (photosynthetic) tissue to decrease as the 

 plant grows older, owing to the encroachment of the fibrous tissue. On holding 

 up a leaf t<j the light, the veinlcts are seen to form a network of fibrous tissue, 

 with meshes of soft tissue l^etween, which are called "vein-islets." The older 

 the plant, the smaller Ijecomes the average area of the vein-ielets, as is well 

 shown in the following table : — 



' Coniell Univ. Agric. Exp. SUtion, Memuir No. 7 (1916). "Senile Changes in I^wives 

 of Vitia vulpina." 



