LESSONS IN BOTANY. 183 



ates food and grows, is a transparent, semi-fluid, albuminous 

 substance, called protoplasm. It is the protoplasm that takes 

 up these mineral compounds and transforms them into the struc- 

 tures and compounds of the vegetable kingdom. It is impossible 

 to distinguish the protoplasm of plants from that of animals. 

 We cannot say that they are the same for the precise nature of 

 living matter cannot be determined, but we know that the "physi- 

 cal basis of life "has in all cases some common characteristics of 

 structure and behavior, diverse as are the ways in which its 

 activity may be manifested. 



Corn, beans, wheat or other grains growing by themselves or 

 in pots with other plants, are interesting objects for observation 

 and comparison, whether in the home or schoolroom. If the tip 

 of the root of a grain of corn or the bean be divided lengthwise 

 with a sharp knife, then moistened with a solution of iodine, it 

 will assume a yellowish or brownish color indicating the presence 

 of protoplasm. If the tip of the root is dipped in a solution of 

 sugar and then moistened with a dilute sulphuric acid, a reddish 

 color will show the presence of protoplasm. 



Sometimes in the lower order of plants, as in slime-moulds, the 

 protoplasm is without form, but in general it occurs in somewhat 

 definite forms of minute size called cells, which are enclosed by a 

 wall of cellulose, secreted by the protoplasm. The protoplasm 

 contains carbon, oxygen, hydrogen, nitrogen, sulphur, and pos- 

 sibly iron ; and in addition the cellulose contains potassium and 

 possibly lime, so that the cell contains the essential elements of 

 the plant. The cell is the unit of all vegetable structures from 

 the simplest to the most complex. In some cases it performs all 

 the functions of a plant; it takes food, grows, reproduces its 

 kind, and dies. 



Free cells are in general somewhat spherical in form, but when 

 grouped in masses they are more or less angular from pressure 

 upon each other, so that they may be cubical, tabular or many- 

 sided. It frequently happens that cells grow more in some direc- 

 tions than in others, and thus elongated cells are formed which 

 are sometimes cylindrical and sometimes angular. The walls of 



