102 Aff ATOMY 01? VEGETABLES. 



The elongation of the radicles downward takes, 

 place by additions to their extremities. The elonga- 

 tion of the plume takes place by an increase of parts 

 already formed. 



The unerring direction of the radicle downward, 

 and of the plume upward, is found, by experiment, to 

 he under the controul of gravitation ; hence, we per- 

 ceive, why plants do not grow perpendicular to the sur- 

 face, which is frequently much inclined, but always 

 stand perpendicular to the horizon. 



CHAP. II. 



ANATOMY. 



In the living vegetable system there are to be con- 

 sidered the exteriour form and the internal constitution. 



Having, in the former part of the work, explained 

 the external characters of plants, we proceed next to 

 an examination of their internal structure. 



Observation, The Anatomy and Physiology of vegetables, al- 

 though a pleasing and important branch of Botanical science, is 

 not absolutely indispensable to the practical botanist, the discrimi- 

 nating characters being taken altogether from external marks. 

 Most of the following observations will be intelligible to every 

 reader, but as the subject is very much connected with the pecu- 

 liar laws which govern living beings, and with the science of 

 chemistry, the young* reader is cautioned not to be dissatisfied 

 with himself, if he should be unable to comprehend them in every 

 particular. 



This chapter will be confined principally to a mere 

 description of the several internal parts ; the next will 

 be appropriated to the various functions these perform. 



The vegetable body consists of the BARK, WOOD, 

 and PITH. 



I. Of the Bark. 



The Bark consists externally of the Epidermis, Cuti- 

 cle, or outer bark, next of the Cellular integument, and 

 internally of the Cortex or inner bark. 



