Chap. 38.] FACTS CONNECTED WITH LEAYES, 37/ 
grassy colour, and has a smooth surface while the veins, the 
callous skin, and the articulations, lie upon the upper face, the 
veins making incisions in the parts beneath, like those to be 
seen upon the human hand. The leaf of the olive is whiter 
above, and not so smooth ; the same is the case, too, with that 
of the ivy. The leaves of all trees turn^^ every day to- 
wards the sun, the object being that the under side may b6 
warmed by its heat. The upper surface of them all has a 
down upon it, in however small quantity it may be ; in some 
countries this down is used as a kind of wool.^^ 
CHAP. 37. THE CAEE BESTOWED ON THE LEAVES OF THE PALM, 
AND THE USES TO WHICH THEY AEE APPLIED. 
"We have already said^^ that in the East strong ropes are 
made of the leaves of the palm, and that they are improved by 
lying in the water. Among ourselves, too, the leaves of the 
palm are generally plucked immediately after harvest, the best 
being those that have no divisions in them. These leaves are 
left to dry under cover for four days, after which they are 
spread out in the sun, and left out in the open air all night, 
till they have become quite white and dry : after this they 
are split before they are put to any use. 
CHAP. 38. — EEMAEKABLE FACTS CONNECTED WITH LEAVES. 
The broadest leaves are those of the fig, the vine, and the 
plane ; while those of the myrtle, the pomegranate, and the 
olive are narrow. The leaf of the pine and the cedar is fine 
and resembles hair, while that of the holly and one variety of 
the holm oak^^ is prickly — indeed, in the juniper, we find a 
55 These statements are quite conformable with the fact. 
This statement is quite true, so far as the fact that the leaves have 
not the same position in the day-time as during the night : the changes of 
position vary greatly, however, in the different kinds. It is generally thought 
that an organic irritability is the cause of this phenomenon. 
This seems to be the meaning of In aliis gentium lana est." He 
alludes, probably, to cotton or silk : see B. vi. c. 20. Thunberg tells us that 
at Roodesand, near the Cape of Good Hope, there grows so thick a down 
on the Buplevrum'giganteum of Lamarck, that it is employed to imitate a 
sort of white velvet, and is used for bonnets, gloves, stockings, &c. 
B. xiii. c. 7. 
Genere ilicum." It is not improbable that he here refers to the variety 
