14 ELEMENTARY ORGANS. 



which prepares its food for nutrition, while the Algae has no 

 such apparatus, but does it by means of exposure on the stem. 

 The distinction between the vegetable and mineral king, 

 doms, is generally more easily made, the transition is more 

 apparent. Minerals are unorganized, and receive no nour- 

 ishment, and of course destitute of the power of assimi- 

 lation ; but increase if at all by external layers. Yet there 

 are substances which have been referred, at different times, 

 both to the vegetable and mineral kingdoms, from the difficulty 

 of determining to which they belong, which has been the case 

 with some cryptogama?. 



3. The science of Botany is generally divided into several 

 subjects for separate investigation : 



1. Tlie structure of vegetables, or vegetable anatomy, con- 

 sisting of a description of the various vegetable tissues, and 

 the organs which these tissues compose. 



2. Vegetable Physiology, or that branch of the science, 

 which has for its object the investigation of the functions of 

 vegetable organs ; or of all that belongs to vegetables as living 

 beings. 



3. The examination of vegetable products. First, as to 

 their constitution forming vegetable chemistry. Second, as 

 to materials administering to the wants of men and animals. 



4. Systematic Botany, or the grouping together the various 

 beings composing the vegetable kingdom, in a manner best 

 suited for studying them, and at the same time affording a 

 correct idea of the peculiar organization of an individual by 

 the group in which it is included. 



We shall not strictly adhere to the above divisions ; but 

 shall include, under one head, much that is properly included 

 in the first two divisions, instead of following the more phi- 

 losophical course above laid down. The interest of the stu- 

 dent will not be sacrificed, but rather promoted by this course, 

 as the knowledge of the constitution of an organ and its uses 

 will be associated. 



CHAPTER I. 



ELEMENTARY ORGANS. 



5. Vegetables are composed of solids and fluids. The sohds 

 are composed of an extremely delicate, elementary, membrane, 

 of an elementary fbre of extreme fineness, and of organic 

 mucus. From one or all of these are formed five classes of 

 tissue, well defined in their characters, viz : 1. Celluler its- 



