PART II. 



VEGETABLE PHYSIOLOGY. 



LECTUKE YI. 



IMPORTANCE OF OBSERVING EXTERNAL OBJECTS. ^VEGETABLES CON- 

 SIST OP TWO SETS OF ORGANS. OF THE ROOT. 



28. The exercises which constitute the principal part of our 

 previous course of lectures, are chiefly designed to assist the 

 student in practical hotany. It is not expected that the young are 

 to be the passive receivers of instruction ; in pursuing the study 

 of Botany it is necessary to compare with real objects, the de- 

 scriptions which are presented. By systematic attention to 

 external objects the mind is disciplined, and prepared the 

 better to pursue abstract studies, where the subjects of inves- 

 tigation cannot, like the plants, be looked at and handled. 



a. All our thoughts, by means of the senses, are originally derived from external 

 objects. Suppose an infant to exist, who could neither hear, see, taste, smell, nor 

 feel ; all the embryos of thought and emotion might exist within it ; it might have 

 a soul capable of as high attainments as are within the reach of any created beings ; 

 but this soul, while thus imprisoned, could gather no ideas ; the beauty of reflected 

 light, constituting all the variety of coloring ; the harmony of sounds, the fragnint 

 odors of flowers, the various flavors, which are derived from our sense of taste, the 

 ideas of soft, smooth, or hard ; all must forever remain unknown to the soul C(ju- 

 fined to a body having no means of communication with the world around it. The 

 soul, in its relation to external objects, may be compared to the embryo plant, 

 which, imprisoned within the seed, would forever remain inert, were no means pro- 

 vided for its escape from this confinement ; and no communication opened, between 

 it, and the air, the light, and vivifying influence of the earth. 



h. Since our first ideas are derived from external nature, is it not a rational con- 

 clusion that we should add to this original stock of knowledge, by a continued 

 observation of objects addressed to our senses ? After the years of infancy are 

 past, and we begin to study books, should we, neglecting sensible objects, seek only 

 to gain ideas from the learned ? or, in other words, should we, in the pursuit of 

 human sciences, overlook the works of God ? 



29. In plants, as well as animals, each part or organ is inti- 

 mately connected with the whole ; and tlie vegetable, as well 

 as the animal being, depends for its existence on certain laws 

 of organization. Vegetable organs may be considered under 

 two classes : 1st, including such organs as promote the growth 

 of the plant, as the root, leaves, &c., called organs of vegeta- 

 tion ; 2d, such as perfect the seed^ and thus provide for t\\Q re- 

 production of the species, called organs of fructijication. 



28. Study of external objects strengthens the mind— Abstract studies facihtated by acquaintance 

 with the natural sciences.— a. Our first ideas gained by the .senses— Analojry l)etwcen tlie soul and the 

 embryo plant.— i. We should not confine our attention exclusively to books.— 29. Vegetable, as well as 

 Bnimal existence, depends on certain laws of organization — Two kinds of organs of vegetables.. 



