INTRODUCTORY HISTOLOGICAL STUDY 
21 
staining nucleus, the surrounding cytoplasm, and the thin and 
delicate cell membrane, with the numerous imprints made upon 
it by adjoining cells. 
Liver Cells. —Use a tiny fragment taken from the freshly cut 
surface of perfectly fresh liver (salamander or small mammal 
recommended). Place this in a drop of physiological salt solution 
upon a clean slide and break it up as much as possible by means of 
mounted needles or fine pointed forceps, thereby making a 
“teased” preparation. Add a cover-slip and then by pressing 
gently upon its surface with the spread points of a pair of forceps, 
further dissociate and spread the material. Study the small 
groups of cells which will lie around the edges of the larger masses. 
Stain with methylene blue. Note in addition to the typical parts 
of the cell, a great abundance of granules many of which escape 
from those cells which have been torn and are thus distributed 
through the preparation, at first masking the cells themselves. 
Note form and size of the cells as compared with those from the 
mouth epithelium. 
Red Blood Cells of Some Amphibian (Salamander or Frog).— 
Mount a little of the blood in a drop of physiological salt solution. 
Cover and study the preparation, staining it with methylene blue 
as in the previous cases. Note that these cells are isolated and 
hence do not show the impress of contact with other cells. Note 
the pale yellow color of the cytoplasm, and the colorless nucleus 
which takes the methylene blue stain readily. Determine the 
the shape of the cell by careful focusing with the fine adjustment, 
and by observing cells in different positions. The cells soon 
become shriveled and distorted, so that fresh mounts should be 
made when needed. 
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2. Cells from Plant Tissues. 
Spirogyra or Some Similar Alga Showing the Arrangement of 
Cells in a Single Row.— Mount in water and cover with cover- 
slip. Note the green chlorophyl, the starch granules associated 
with it and stained a deep blue by application of a weak solution 
of iodine in an aqueous solution of potassium iodide (which at the 
same time stains the nucleus brown, an illustration of differential 
staining), the large vacuoles, and the relatively small amount of 
