78 
REPORT ON BOTANY, MDCCCXLI : 
MOSSES. 
On the Structure of the Setce of Funaria hygrometrica, by 
Edwin Lankester ; Annals of Natural History, vol. iv. p. 362. 
The fruit-stalks of this well known moss have already long 
been known to possess hygroscopical qualities. The author 
instituted a more particular examination with regard to them 
in this respect. On taking a dry fruit-stalk into one’s hand, 
and moistening the lower part with the finger, the capsule will 
turn itself from the right to the left, by making two, three, or 
more turns ; on moistening the upper part in the same 
manner, the capsule turns itself still more rapidly in an oppo- 
site direction. On a microscopical examination, the whole 
stalk was found to consist of lengthened cellular tissue, which 
is twisted in a spiral form. The cellular tissue is not, how- 
ever, turned uniformly, but at two-thirds of the length of the 
stalk it commences to assume a straighter form, and at the 
upper part it again turns itself, but more acutely, in the op- 
posite direction to that of the lower part. The cause of the 
turning depends on this direction of the cellular tissue. It 
may be left to discussion, whether the moisture renders the 
tissue straighter in consequence of extending it, or whether 
it originates from the mere distension of the external tissue. 
The capsule turns itself in an opposite direction to the spires 
of the wetted end, and the circumstance of its turning more 
rapidly on the upper end being wetted, depends on the more 
acute angle made by the upper spires. But the dryness of the 
fibres is not the sole cause, for the green fruit-stalks, although 
perfectly dried, do not turn when moistened. But as the cap- 
sule turns itself towards the earth at the period of ripening, 
it is probable, that the turning of the fibres already existing 
becomes stronger, and thus the movements are produced. 
By the controversy which was at one time carried on be- 
tween De Saussure and He Luc, it has been established, that 
dry vegetable fibre is shortened by moisture, but that the 
animal fibre is lengthened by it. Probably because the former 
is hollow, and is distended by the imbibed fluid, and thus 
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