5 8 THE SCIENCE OF LIFE. 



Within this membrane the bioplasm is, as it were, im- 

 prisoned, yet receiving pabulum by endosmose, or 

 through pores left in the membrane, its vital functions 

 remain. In the higher plants, as the palm or the oak, 

 the structure is but an aggregation of cells, some of 

 which have been modified in form to serve special uses. 



8. Near the vegetable cell-wall the bioplasm appears 

 less fluid than in the middle of the cell, and certain chem- 

 ical agents cause a partial separation from the membrane, 

 so as to present, under the microscope, the appearance of 

 a secondary and gelatinous membrane the primordial 

 utricle. 



In some vegetable cells the molecular movement of 

 the contained bioplasm is quite evident, and has re- 

 ceived the name of Cyclosis. It may be seen under the 



FIG. 8. Three cells from the hair of a potato, showing Cyclosis. Bioplasmic threads 

 proceed from the nuclei, along which the current flows, in the direction of the arrows. 



microscope in the stinging hair of the nettle, and in 

 hairs from the calyx of Tradescantia Virginica, etc. 

 (Fig. 8.) 



9. Within the cell-wall the bioplasm may be trans- 

 formed into chlorophyll, or green coloring matter, into 

 starch, gum, oil, resin, sugar, or other kind of formed 

 material or mineral substances may crystallize in the 

 cells, forming what are known as raphides. The variety 



