PLANT-CELLS AND THEIR CONTENTS. 



297 



The unicellular hairs found on young leaves of Yerbena urticifolia, 

 a common way-side weed, exhibit something like a nucleus at the base 

 of the hair, from which center streams of protoplasm are constantly 

 departing, to which they constantly return (Fig. 13). Fig. 14 shows 

 the terminal cell of a hair taken from the petal of the purple lady's- 



Fig. 13. Unicellular Hair of Verbena. Fig. 14. Hair from Petal of Lady's Slippee. 



slipper. Here the nucleus seems almost to be in the way. It is so 

 large as nearly to close the narrow cell across from side to side, and 

 the current appears crowded between the nucleus and cell-wall. 



In the hairs that cover the common tomato-plant we may find 

 beautiful transparent cells. In these cells sometimes the nucleus shows 

 a vacuole, and the streams are always fine and large, but changeful as 

 the shadows of passing clouds (Fig. 15). 



But we must resort to plants belonging to the botanical order Cu- 

 curbitacece to find hair-cells showing greatest activity. In the hairs 

 covering the forming bud of a common pumpkin-vine the cells are of 



