FIBRE. 
15 
thickness by successive deposits, so that the spiral 
thread becomes a flattened band or even a ring, like a 
FIG. 5 . 
Ceils from the testa of the seed of Collomia grandiflora. 
quoit, as in Fig. 6, which represents cells of Opuntia 
vulgaris , with fibres in various stages of development. 
FIG. 6. 
Ceils with thickened fibres from Opuntia vulgaris. 
