32 ON ROOTS. 



loosened by digging, they are scarcely ever pulled up en- 

 tire. 



Mrs. B. The root of these plants is called fusiform, or 

 spindle-shaped. It is also called the tap root, From its 

 tapering so considerably toward the end ; and the pivot- 

 root, owing to its fixing the plant so immovably in the 

 earth. This root is but scantily provided with the means 

 of acquiring food, having sometimes not more than a sin- 

 gle fibre furnished with a spongiole at its extremity. To 

 compensate for this disadvantage, the root is of so moist 

 and fleshy a nature as to afford an ample store of provision. 



Caroline. But with such limited means of suction, 

 how can this magazine be replenished ? 



Mrs. B. The surface of the ground immediately ex- 

 posed to the drying powers of the sun and wind, retains 

 less moisture than the deeper and more sheltered strata 

 of the soil ; besides, the store is laid up during the season 

 of abundance, and measured out, as the necessities of the 

 plant require, during that of dearth. Here, you see, are 

 a variety of compensations for its circumscribed power 

 of absorption. 



A very simple experiment will convince you, that the 

 spindle-shaped root, as well as those of every other de- 

 scription, absorb water only by the spongioles at their ex- 

 tremities. If you immerse a young radish in a glass of 

 water, so that every part of it shall be covered except the 

 taper end of the root, you will find that it will soon die ; 

 while, if you immerse only the extremity of another rad- 

 ish in water, you will preserve it alive. The whole body 

 of the root serves to fix and support the plant in the soil, 

 but it is the extremity alone which absorbs nourishment.* 



It sometimes happens that this species of root, whether 

 from want of vigor or some mechanical impediment, is 

 checked in its growth, and wears the appearance of being 



* Beets, Carrots, Parsnips, &c. are also of the spindle shaped species. 



122. What is the root of it called'? 123. Why is it also called 

 tap-root, and why pivot-root! 124. What compensation is made for its 

 having but one fibre more with a spongiole'? 125. What compensation 

 has it besides that of inherent moisture'? 126. What simple experi- 

 ment is named as showing that the spindle-shaped root, as well as those 

 of every other description, absorb water only by the spongioles at their 

 extremities'? 127. What roots mentioned in the note are of the 

 spindle-shaped species? 128. By what name is the spindle-shaped 

 root called when mutilated 1 



