ROOT-HAIRS AND ROOT-CAPS 35 
Cut about I cm. from the tip of a root containing 
root-hairs, mount it in water and study it under the low 
power. Crush the root by lightly pressing on the cover 
glass. With the high power work out the relation be- 
tween the root-hairs and the cells of the roots. Note the 
vessels and fibers in the central portion of the roots. 
Draw a single root-hair showing its connection with the 
root in detail. Work out the history of the development 
of root-hairs by studying those found near the tips of 
the roots and illustrate by making three outline drawings 
showing different stages in their development. 
Note that the root-hairs and the cells of the root 
contain a grayish granular substance called protoplasm. 
Put a little 10 per cent. salt or sugar solution on some 
root-hairs that are still quite short. If the solution is 
of the proper strength, the protoplasm will draw away 
from the cell wails. Cells thus affected are said to be 
plasmolyzed. Draw a plasmolyzed root-hair. Remove 
the salt or sugar solution by replacing it with fresh 
water. Does the protoplasm again return to its natural 
position? The instructor will explain the cause of this. 
What is the chief function of root-hairs? Pull up a 
plant growing in soil and note the relation between the 
particles of soil and the root-hairs. 
Mount several root-tips in water and study the root- 
caps. Note the loose cells along the outer surface. Care- 
fully study longitudinal sections of root-tips of onion 
which have been stained red. Note the root-caps and the 
growing point immediately back of it. Make an enlarged 
outline drawing of the root showing the cap and a few 
cells in the growing point. 
