THE LOWEST FORMS OF LIFE. 55 
constant, or in imperfect temporary cavities framed for the pur- 
pose. 
And this distinction holds good in the perfectly-formed 
animal and vegetable, such as the man and the tree, as well as 
in the lowest known types of either kingdom ; so you see we 
are reminded at every step of the unity of those laws by which 
nature is controlled. 
Bearing in mind that it derives the nutriment that ministers 
to its growth from the inorganic constituents of the water, you 
will, of course, see that our little vegetable cell must not remain 
long in one place, lest it should exhaust the supply around it, 
and it is therefore furnished with one or more little whip- or 
hair-like members, by means of which it moves rapidly from 
place to place. If you had carefully examined the little forms 
that moved about the Volvox, you would have perceived these 
members of locomotion. (PI. v. and pi. vi. fig. 1.) 
The ‘ cilia 3 (as these hair-like fibres have been very appro- 
priately called, from the Latin word cilium, an f eyelash 3 ) have 
an inherent contractile power, similar to that of the sensitive 
plant, and so long as there is vitality in them they are in con- 
stant motion. You may, perhaps, be surprised when I tell you 
that we have vast numbers of them at work in various parts of 
our bodies, which, unconsciously to ourselves, keep certain of 
the fluids in active circulation ; and in the living oyster they 
may be seen to perfection; so, you see, they are common to 
animals as well as plants. But to return to our little living cell. 
If there is any subject into which scientific men have 
imported a terrible array of hard words, it is into the history 
of this simple little object ; and if I were to begin to discourse 
learnedly to you about ‘ primordial utricles/ ‘ cytoblasts/ 
‘ endoplasts/ and f protoplasma/ I am sure you would all be 
fast asleep before I had finished my explanation of the meaning 
of one of these terms in connection ‘with the anatomy of a 
vegetable cell. 
Without at all sacrificing to scientific accuracy, however, I 
am fortunately able to borrow a very clear and simple descrip- 
tion of this object from a work recently published in connection 
with the microscope.* It is ‘a closed sac, composed of an 
(< originally ) imperforate membrane formed of the chemical sub- 
stance called cellulose, this membrane inclosing fluid contents 
so long as the cell retains its vitality 3 33 
“ That may be a very clear and simple description of a 
vegetable cell to you or any other scientific student/’’ said my 
young pupil, “ and I believe that I understand its meaning ; 
* Griffith and Henfrey’s “ Micrographic Dictionary,” page 126, article 
“Cell.” Van Voorst. I860. 
