VEGETABLE CYTOLOGY 
39 
granular-looking. Within the cytoplasm will be observed a number 
of clear spaces. These are vacuoles and because they are filled with 
cell sap (water with nutrient substances in solution) are called “ sap 
vacuoles 
Protoplasm is in intimate relation to water. The reaction of the 
cytoplasm to a bounding film of water between it and the cell wall 
forms the outer plasma membrane or ectoplasm, a clear homogeneous 
outer band of cytoplasm; the reaction of cytoplasm to the water 
within the sap vacuoles forms the vacuolar membranes; the reaction 
of the dense protoplasm of the nucleus to the water in the cytoplasm 
around it forms the nuclear membrane. Upon mounting another 
portion of epidermis in iodine solution, removing the excess of stain 
and adding a drop of sulphuric acid and then examining under high 
power, we note that the cell walls of cellulose are stained a deep blue. 
A yellow line is evident in the middle of each cell wall and separates 
each cell from its bounding cells. This fine is the middle lamella 
which is composed largely of calcium pedate. 
PROTOPLASM AND ITS PROPERTIES 
Protoplasm, or living matter, is the more or less semi-fluid, viscid, 
foamy, and granular substance in which life resides. It is the 
“physical basis of life.” 
The peculiar properties which distinguish protoplasm from non- 
living matter are as follows: 
1. Structure. — Protoplasm invariably exhibits structure. No por- 
tion of it, however small, has been found to be homogeneous. Each 
advance in microscopical technique reveals new complexities. The 
protoplasm of a single cell, far from being a single unit, must rather 
be looked upon as a microcosm. 
2. Metabolism. — Perhaps the most significant peculiarity of living 
matter is found in its instability and the chemical changes which 
continually go on within it. It is constantly wasting away, and as 
constantly being built up. These losses and gains are not upon the 
exterior surface, but throughout its mass. Its growth and renewal 
are by intussusception, or the taking in of new particles and storing 
them between those already present. A bit of protoplasm may re- 
