

SHAVINGS EXAMINED MICROSCOPICALLY. 563 
tissue is made up for the most part of this cellulose, arranged 
in different forms, all, however, derivable from the simple: 
sac or cell, which is the basis and foundation, morphologi- 
cally, of the whole vegetable kingdom; being found in its 
simple and uncomplicated form in the Protophe yta, or first 
plants, we have mentioned, and modified in outline to a 
greater or less degree in the different parts of the tree, 
stem, leaves, and flowers. There is a doubt, however, in 
the minds of some physiologists as to whether the hard 
parts of plants are made up of this substance cellulose, or a 
modification of it termed “lignine.” This point is one which 
we will not consider, as it is extremely doubtful if either of 
these two compounds has been obtained pure and separate 
from the other. 
If a slice be made with a very sharp knife of some ripe 
fruit, as an apple or an orange, it will be observed on view- 
ing such a section by means of the microscope, that it is 
made up of almost symmetrical and equal sized little sacs 
or cells, as they are called; and such simple tissue is known 
as cellular tissue. But if a similar slice be made of such 
hard matter as wood, a very different appearance will present 
itself to our eyes. First, however, so as to make ourselves 
acquainted with the manner in which such simple cellular 
tissue (where the elementary sacs merely touch each other 
with very little mutual pressure) passes into the more com- 
plex woody tissue, take a similar slice from the stem or 
young rootlet of some herbaceous plant, as the garden 
rhubarb or other common vegetable. Such a slice, made as 
thin as possible, is now placed i in a little water upon a glass 
“slide,” and, with a thin “cover” over it, examined by means 
of a microscope which does not magnify too strongly. We 
now see that the tissue in this case is cellular, as well as that 
in the fruit, but that the individual cells have become much 
altered in appearance from mutual pressure, which in some 
cases has been equal upon all sides, in others greater in cer- 
tain directions than in others. So they have been crowded 
