FIBRE. 
13 
In a portion of cuticle taken from an Aloe , the tubercles 
are so large as to give the membrane a, rough appearance 
even to the naked eye. 
FIBRE. 
Fibre, although at one time regarded as an element 
of vegetable tissues, is now generally looked upon as 
a secondary formation deposited within the walls of 
cells, or, in other words, on the internal surface of 
membrane. It is solid, sometimes transparent, and 
generally speaking of a greenish- white colour, though 
in some few plants, as in the elaters of Jungermannia , 
it is more or less red. Its direction, as shown in 
Figs. 5 and 6, is most frequently spiral, the spires run- 
ning from right to left ; in some plants, however, the 
direction is from left to right. According to Lindley, 
it is straight in the lining of the anther of Campanula 
and Digitalis purpurea. Fibre varies considerably in 
size ; in some plants it exceeds ^th of an inch in 
diameter, in others, it surpasses in delicacy the finest 
hair; it generally adheres very firmly to the sides of 
the cell-wall, especially in the young state, when the 
turns of the spiral are very close together, but as the 
cell elongates, the fibre sometimes keeps pace with it, 
and the turns are more widely separated. Two or 
more contiguous turns are very prone to anastomose, 
