LECTURE VI. 
FIBRO-CELLULAR TISSUE. 
We now arrive at a class of cells which, for the sake 
of distinction, may be termed compound, from the 
circumstance of their being composed of membrane and 
fibre ; they occupy definite positions in plants, and form 
the tissue known as the fibro-cellular. The cells are of a 
more or less oval figure, and the fibre often attains a 
very large size, even as much as 3 -^ 0 th of an inch. 
Fibro-cellular tissue is common in the leaves of manv 
orchidaceous plants, and occurs abundantly in the testa 
of seeds. I have already mentioned the existence of 
this tissue on the testa of the seed of Collomia grandi- 
Jlora , in which the cells containing a spiral fibre are 
protruded from the surface after the seed has been 
moistened with water. The leaf of an Orchis, Pleu- 
rothallis ruscifolia, exhibits, by vertical section, a large 
