AQUATIC PLANTS USEFUL TO THE MICROSCOP-IST. 57 



soft, colorless, jelly-like substance called vegetable 

 protoplasm, and the small-green grains (the chlorophyl) 

 which give the greeri color to the plant. In Andcharis 

 the walls of the leaf cells are transparent, so that the 

 microscope shows a part of what is taking place within 

 the cell ; and it is a wonderful sight, for the protoplasm 

 is slowly moving around the walls, carrying the 

 chlorophyl grains with it. Up one side of that micro-, 

 scopic cell travels the strange procession; across, 

 down, and up, slowly and steadily the stream and the 

 grains move round and round. Sometimes a little 

 thread of colorless protoplasm leaves the main cur- 

 rent and starts across by a shorter road, and some- 

 times the current pauses, stops, and refuses to move 

 again. The streams in two cells lying side by side 

 may flow in the same or in opposite directions, with 

 only the thin wall between them. What causes these 

 remarkable movements is not known. Cold seems to 

 retard, and warmth to hasten the flow, and often, 

 when the chlorophyl has increased so that the green 

 grains crowd the cells, the circulation ceases appar- 

 ently because the chlorophyl has not left enough' 

 space for free movement. .The botanists call' this cir- 

 culation of the protoplasm cyclosis. It is also finely 

 seen in the long, narrow, ribbon-like leaves of 

 Vallisneria, an abundant and common plant in slowly 

 flowing streams. 



To show the cyclosis, the Anacharis leaf needs only 

 to be cut close to the stem, placed in the cell in water, 

 covered by a thin glass, and examined by a high-power 

 objective. The one-inch lens will not. show it dis- 

 tinctly. 



The plant is a fruitful source of supply for our two 



