12 
Wound healing in a species of Oak 
oaks. The broad rays are supposed to have arisen phylogenetically 
by the fusion of uniseriate rays. Bailey' has arrived at the same 
conclusion from an investigation of the traumatic wood of several 
species of Quercus. In the immediate neighbourhood of a severe 
wound he found only uniseriate rays produced, though a slight 
injury occasionally caused the abrupt formation of broad rays. 
Groom 3 has recently reviewed the position and has given it as his 
opinion that “it is impossible at present to decide whether in 
Quercus the broad-rayed or the narrow-rayed type was primitive.” 
He has also suggested the possibility of the origin of broad rays in 
Quercus and Alnus by a fusion of small rays as being merely of 
physiological significance. 
The European species Quercus pedunculata is not included 
among the species whose traumatic tissues were examined by Bailey, 
and it is interesting to notice that its behaviour when wounded is 
not entirely in accordance with the results obtained by the above 
investigator, since severe wounding does not invariably cause the 
production of uniseriate or non-aggregated small rays, but occa¬ 
sionally also the abrupt formation of broad rays. 
The writer wishes to express her gratitude to Professor Seward 
for facilities for working at the Botany School, and for advice in the 
above investigation. 
Botany School, 
Cambridge. May, 1912. 
* Bailey, I. V. “ Traumatic Oak Woods.” Bot. Gaz., 50: 374-380. 
2 Groom, P. “ The Evolution of the Annual Ring and Medullary Rays 
of Quercus.” Ann. Bot., Vol. XXV, No. C, October, 1911. 
Description of the Photographs on Plate II, 
Illustrating Miss Duthie’s Paper on Wound Healing 
in a Species of Oak. 
Fig. 1. Photograph of slab of wounded oak, shewing the the deal peg and 
the several wounds described in the text. 
Fig. 2. Photograph of transverse section of wound-wood outside em¬ 
bedded peg at the junction of heart and sap-wood, shewing the “com¬ 
pounding ’’ of narrow medullary rays. 
Fig. 3. Photograph of tangential section of callus-wood outside jagged 
end of deal peg, shewing changed shape of rays and twisted course of 
xylem elements. 
Fig. 4. Photograph of transverse section of abnormal callus-tissue 
formed by the fusion of club-shaped outgrowths from exposed medullary ray 
cells, shewing regularly arranged groups of very thick-walled fibres in bands 
alternating with thick-walled wood parenchyma often arranged concentrically : 
also crushed tanniniferous cells (dark). 
