DEVELOPMENT AND FUNCTIONS OF CELLS. 43 



knowledge of which rest the very foundations of scientific 

 botany. 



51. The Plant-cell, as it is termed by Dr. Schleiden, con- 

 stitutes an entire vegetable, without organs, imbibing its food 

 by endosmosis through every part of its surface, which it con- 

 verts into the materials of its own enlargement and growth, 

 and finally into new cells which constitute its progeny. Being 

 without lateral compression of any kind, the plant-cell neces- 

 sarily takes a globular form. We select, as an illustration of 

 the plant-cell, the Protococcus nivalis, or red snow-plant, 

 found in the arctic regions, and which also occurs on damp 

 ground in much lower latitudes. In Fig. 17, 1, we have 



several individuals of this plant slightly magnified to show the 

 nature of the reproductive process. New cells are seen to 

 originate in the interior of each plant-cell, which gradually 

 take their place, and the new generation thus produced enlarges 

 and gives rise to a new progeny in their interior as before. 

 In this manner, this simple vegetation grows on from age to 

 age : 4 represents a more highly magnified individual of the 

 Protococcus nivalis, showing more distinctly the new cells 



