26 ON ROOTS. 



Caroline. That is very true so far as regards the for- 

 mation of the seed ; but its bursting, and the sprouting 

 of the young plant, appears to be the natural commence- 

 ment of the history of vegetation. 



Mrs. B. The germination of the seed is a process so 

 intimately connected with its formation and composition, 

 that it is a reciprocal advantage to treat of them together, 

 or, rather, in immediate succession, instead of separat- 

 ing them by the intervention of the whole history of 

 vegetation. 



CONVERSATION II. 



ON ROOTS. 



Mrs. B. We are now to examine the structure of 

 those organs, whose office it is to nourish and preserve 

 the plant. 



In the nutrition of plants, six periods are to be dis- 

 tinguished : 



1. The absorption of nourishment by the roots. 



2r The transmission of nourishment from the roots 

 to the different parts of the plant. 



3. The development of the nourishment. 



4. The action of the air on plants. 



5. The conversion of nourishment into returning sap 

 or cambium. 



6. The secretion of various juices from the sap. 



Plants being deprived of locomotion, as we have ob- 

 served, cannot go in search of food : it is necessary, 

 therefore, that nature should provide it for them in their 

 immediate vicinity. Those simple elements, which are 

 almost every where to be met with, water and air, con- 

 stitute this food. Water not only forms the principal 

 part of it, but serves, also, as a vehicle to convey what 

 solid food the plant requires; and as a vegetable is un- 

 furnished either with a mouth to masticate, or a stomach 

 to digest, solid food can be received only when dissolved 



83. How many periods are there in the nutrition of plants! 84. 

 What are they! 85. Why is it necessary that nature provide food 

 for plants in their immediate vicinity! 86. What constitute the food 

 of vegetables'? 87. How can solid food be received by them! 



