314 
the constriction at the base nor on the plug, but as far up as 
the base of the latter. The stage in fig. vi. shows this cutinous 
layer covering the apex and in figs. vii.-xi. the plug is shown 
being pushed through the terminal cap of cutin, thus the blunt 
hairs start with a complete covering of cutin, and later, just 
before or just after they are exposed by the growth of the leaf 
sheath on which they are seated, this cap is broken through, 
and the plug projects. It is not till this stage is reached that any 
external oilisfound. After this stage oil is to be seen both on the 
blunt and pointed hairs. There is nothing to indicate that oil 
is excreted from the pointed hairs, and the oil occurring on them 
is regarded as having come from the blunt hairs during inclosure 
by the next older leaf sheath. In the mature blunt hairs oil is 
seen in the cavity at the base in the form of globules, and also 
towards the apex, and in the lumen from about 2 of the length 
to near the top of the hairs there is a refractive substance whose 
nature was not determined. In the mature pointed hairs a 
certain amount of oil was found (fig. iii.), but in no other part 
of the plant was any oil detected. 
“Tt cannot be supposed that the oil ae from the hairs 
would pass through the lateral walls, and it is questionable 
whether the oil escaping from the blunt hairs rane permeate the 
plug at the top of the hair, it seems more likely that the plug may 
act like the loose stopper of a bottle and allow the oil to ooze out 
between it and the wall. It was found in staining the contents 
of the mature uninjured hairs, that the stains were able to pene- 
trate through the base of the hairs faster than through the apex. 
“From the foregoing it would appear that the oil is secreted 
only in the two types of hairs, and that it is from the blunt ras 
only that it escapes just after the continuous cutinous ca 
broken and the plug extruded. The cap appears to be broken Fast 
before or just after the hairs become exposed and it is conjectured 
that the oil is enabled to pass out by the temporary lifting of 
the plug.” 
The oil of the grass was examined at the Wellcome Chemical 
Research Laboratories by Dr. T. A. Henry, who kindly supplies 
the following results of his investigations :— 
“The material examined consisted of fresh plants grown at 
the Royal Botanic Gardens, Kew, and included the following 
samples. 
a. grass grown in pots or boxes under cover, 12 pounds. 
b. grass grown in the open, 30 pounds. 
‘‘ Both samples have a characteristic aroma, recalling that of 
cumin seed, which is no doubt the odour which Mr. Dawe, in his 
memorandum on the grass, describes as similar to that of curTy- 
The aroma seemed to be much stronger in the plants grown under 
cover than in those grown outdoors. 
“The substance to which the odour is due is exuded as 4 
yellowish oil from glandular hairs, which are easily visible on 
