AN OUTLINE OF THE FIRST PRINCIPLES OF BOTANY. 



1. Plants are not separable from animals by any absolute character ; the sim- 

 plest individuals of either kingdom not being distinguishable by our senses. 



2. Animals are for the most part ^incapable of multiplying by mechanical or 

 spontaneous division of their trunk. 



3. Plants are for the most part congeries of individuals, multiplying by sponta- 

 neous or artificial division of their trunk or axis. 



4. Generally speaking, the latter are fixed to some substance from which they 

 grow, are destitute of locomotion, and are nourished by absorption through their 

 cuticle (38). 



5. Plants consist of a membranous transparent tissue, formed by a combination 

 of oxygen, hydrogen, and carbon, to which azote is occasionally superadded. 



6. Their tissue appears under four forms, viz. cellular tissue, woody fibre, spiral 

 vessels, and ducts. These are called elementary organs. 



I. ELEMENTARY ORGANS. 



7. Of these Cellular Tissue (Tela cellulosa, hat. ; Tissu cellulaire, Fr. ; Pulp 

 and Parenchyma, of old writers ; Zellgewebe, Germ.) is the only form universally 

 found in plants ; the other forms are often either partially or entirely wanting. 



8. Cellular tissue is composed of transparent vesicles, the sides of which are not 

 perforated by visible pores (17). 



9. Each vesicle is a distinct individual, cohering with the vesicles with which 

 it is in juxtaposition. 



10. Therefore, the apparently simple membrane that divides two contiguous 

 cells is in fact double. 



11. If the adhesion of the contiguous cells be imperfect, spaces will exist be- 

 tvveen them. Such spaces are called intercellular passages. 



12. The vesicles of cellular tissue, when separate, are round or oblong ; when 

 slightly and equally pressed together, they acquire an hexagonal appearance ; 

 stretched lengthwise, they become prismatical, cylindrical, or fusiform. 



13. Cellular tissue, the vesicles of which fit together by their plane faces, is 

 called parenchyma. 



14. Cellular tissue, the vesicles of which are elongated and overlie each other at 

 the extremities, is called prosenchyma. 



15. Parenchrjma constitutes all the pulpy parts of the medulla or pith (82), 

 the medullary rays (113), a portion of the bark (102), and all that is interposed 

 between the veins of the leaves and of other appendages of the axis. 



16. Prosenchyma is confined to the bark and wood, in which it is mixed with 

 woody fibre (19). 



17. The function of the cellular tissue is to transmit fluids in all directions ; 

 the membrane of which it is composed is, therefore, permeable, although not fur- 

 nished with visible pores (8). 



18. It has been supposed that the cellular tissue is self-productive, one vesicle 

 giving birth to many others. 



19. Woody fibre (Vasa fibrosa, Lat. ; Tissu cellulaire allonge, Fr. ; Clostres, 

 Fr. ; Bastrohren, Germ.) is tissue consisting of elongated tubes tapering to each 

 end, and, like the vesicles of cellular tissue, imperforate to the eye. 



20. It may be considered a form of the cellular tissue, itself, to which it is fre- 

 quently referred. 



21. It is found in the wood, among the parenchyma of the liber (104), and in the 

 veins of leaves, and of other appendages of the axis. 



22. Its functions are to give strength to the vegetable fabric, and to serve as a 

 medium for the passage of fluid from the lower to the upper extremities. 



