94 



ANATOMY OF STEMS, ROOTS, AND LEAVES 



a cell was protoplasm which may he either naked or enclosed in 

 a cell-wall, or a small microscopic chamher from which the 

 protoplasm has been withdrawal. 



The protoplasm is an albuminous substance more nearly like 

 the white of an egg than any other substance with which we can 

 compare it. It is that part of the plant in which the life is 

 said to exist, and, so far as we know, is not different from the 

 protoplasm of the animal cell. In its active condition, it is 



66. — Cross-section of monocotyledonous stem showing arrangement of the fibro- 

 vascular bundles. 

 Fig. 67. — Cross-section of dicotyledonous stem showing arrangement of fibro-vascular 

 bundle. 

 Fig. 68. — Parenchyma cells. 



very sensitive to change of humidity, temperature, and to poison- 

 ous substances. The active growing cells of the plant are rich 

 in protoplasm, but many cells which persist throughout the 

 entire life of the plant die and lose their protoplasm. In fact, 

 the great bulk of the cells of most of our higher plants is dead. 

 The cell can be studied to the best advantage in some of the 

 water plants, especially the algae, which will be studied later. 

 If we examine a very small amount of one of these plants known 

 as Spirogyra under the microscope, we find that it is made 

 up of a single row of elongated cells placed end to end. These 

 cells appear to be rectangular, but they are cylindrical tubes 

 closed at both ends. We very readily recognize the cell-wall and 

 the chlorophyll, which is in a body known as the chromatophore. 



