Menuy and Flood — The Dunkcld Ilijbrid Lurch. 65 



glancing incidence, and is lost to the leaf as far as photosynthesis is con- 

 cerned. Where tlie epidermis is papillose, liowever, much of tliis light is 

 forced to penetrate the epidermis, and is deflected into ilie leaf, where it is 

 available for pliotosyntliesis. The effect may be illustrated experimentally 

 by allowing very oblique illumination to fall upon the ridged surface of 

 so-called ' prismatic ' glass, used in basement windows, etc., when the slieet of 

 glass viewed from its smooth surface appears to glow with light. If a piece 

 of smooth glass be substituted for the ' prismatic ' glass, tlie oblique light 

 fails to penetrate it, and no such effect is produced. 



" It seems probable that photometric measurements could be made of the 

 gain of light in papillose leaves, and I hope shortly to make experiments on 

 the subject." 



NOTES BY PEOFESSOE A. HENEY. 



' The microscopical details and Fig. 1 are due to Miss Flood. For the rest 

 of the paper, I am mainly responsible. For help in obtaining material I owe 

 thanks to Mr. A. Murray, forester at Murthly, to his son, Mr. J. M. Murray, 

 BSc, and to Mr. D. Keir, forester atDunkeld. 



Since the date of the reading of this paper, the Duukeld hybrid larch has 

 been described and named x Larix Henryana, by Mr. Alfred Eehder in 

 Journal, of the Arnold Arloretiom, vol. i, page 52 (July, 1919). Mr. Eehder 

 had not seen cones of^this tree, and his description relates to the naked-eye 

 characters of the twigs and leaves of young trees, about twelve feet tall, 

 which were obtained from Dunkeld, and are now growing in the Arnold: 

 Arboretum, Boston, U.S.A. This name is invalid, being later than Larix 

 etcrolepis, which was publislied by me with a short but adequate descripciou 

 in the Irish Times, 24th June, 1919, page 4. 



The Dunkeld hybrid larch was apparently first mentioned l)y Mr. H. J. 

 Elwes, who states in Elwes and Henry, " Trees of Great Britain," vol. ii, page 

 388 (1907), that at Dunkeld there was a Japanese larch planted close to a 

 common larch, from which seedlings were raised at his suggestion by the late 

 D. Keir, which seemed to be hybrids between the two species. 



All the plantations of Dunkeld hybrid larch wliich I have seen are 

 remarkable for their great vigour and good health, being free from chermes 

 and fungus disease. Al Tubney Arboretum near Oxford, a group of fourteen 

 trees planted in 1909, varied in 1913 from 10 ft. 7 in. to 6 ft. 8 in., averaging 

 8 ft. 5 in. in height. These are now (September, 1919) narrow in iiabit, with 



