GROWTH OF FERNS. 
19 
stones •; the young ferns are beginning to grow, but only 
the strongest will live. This green scum must now be 
observed under the microscope. Taking up a small por¬ 
tion with the tip of a needle which has been previously 
inserted in a small wooden holder, place it carefully in 
the centre of a glass slip three inches by one inch ; cover 
with a small circle or square of thin microscopical glass, 
commonly sold by most opticians, and allow water to 
flow under by capillary action. If this green matter 
is now observed under the half or quarter inch power of 
a fairly good microscope, and daily by taking a minute 
particle from the general mass, the following process 
of growth can be gradually seen. The first appearance 
of the green scum under the microscope will show the 
fern spores (fig. 11, a , b , c) germinating by the pro¬ 
trusion of a tubular-like process of a pale-green colour; 
from this, by cell-division, gradually enlarges a kind 
of flat scale (fig. 11, d) called the prothallus; when 
it is completely formed, filamentous rootlets spring from 
the under side, and if closely observed, some of the 
cells will be seen to produce antheridia, which answer 
to the male organs (stamens) of the flowering plants. 
