THE NATURE AND NEEDS OF LIVING MATTER 37 



Note. Where cells are united, whether in plant or animal 

 structure, they are said to form tissues. Thus there is nerve 

 tissue, muscle tissue, etc., in animals, and there are many 

 other tissues in Dlants. 



FIG. 9. Drawings of sections of cells. Showing some various sorts much 

 magnified. 6, bone cell; c, epithelium cell from the intestine; e, flat 

 epithelium cell from the mouth ; /, fat cell ; n, nerve cell from the brain ; 

 m, muscle cell. 



4. (Optional.) Sketch a few of the cells stained with methyl green, 

 especially showing cell walls, nuclei, and relations to one another. 



Conclusions. 1. Distinguish between one-celled and many- 

 celled plants or animals. 



2. In what ways are plant and animal cells alike ? How 

 unlike ? 



3. What are tissues ? W T hat is the unit of their structure ? 

 Note. Tissues are grouped in both plants and animals to 



form organs, as a leaf, a root, the hand, the eye, etc. 



b. Simple Properties 



Note to Teacher. Spirogyra, or pond scum, stamen hairs of 

 spiderwort (tradescantia), leaves of nitella, vallisneria, elodea, 

 or the root hairs of almost any aquatic plant are good for 

 this exercise. Unless time is no object, it is likely better 

 simply to set up a few microscopes with any of the above 



