INTRODUCTORY WORK 13 
Study the objects carefully, noting size, form, and struc- 
ture. Is the surface of the sand smooth? How do the hair 
and paper fibers differ in structure? Place a needle or pin 
point on the cover-slip and compare it with the ends of the 
hair and fibers. Sketch the hair as large as it seems to you 
to be both with and without magnification. See whether 
you can observe anything as to the form and structure of 
the sand and fibers without magnification. Remove the ma- 
terials, and carefully clean and dry the slide and cover-slip. 
Study of a plant-cell_—By use of the forceps or needles 
remove one or two leaves from a moss plant, and mount 
as previously directed. Study first with the low power, then 
with high power. Note the cells appearing as sections com- 
posing the leaf, their walls appearing almost colorless. 
Have adjacent cells a wall in common? Within the cells 
are bodies called plastids, and those in this cell, being green, 
are called chloroplastids. About how many plastids are 
there in acell? What is their form? The very lightly gran- 
ular material, the cytoplasm, can be seen just within the 
wall and among the plastids. Usually in fresh unstained 
material the nucleus can not be seen. Draw a group of two 
or three cells. 
All plants are composed of cells, and in different plants 
or in different parts of a plant they may vary greatly in 
size and form. In numbers of cells plants range from those 
whose adult body is a single cell to those in which it is 
made up of millions of cells. 
* Under a demonstration microscope there should be placed a pre- 
pared mount showing the cell structure, including the nucleus. 
