PART I. 



THE FORMS OF TISSUE. 



CHAPTER I. 



CELLULAR TISSUE. 



General Iniroduciory Remarks. 



Sect. i. The'general properties of cellular tissue are indicated by this name, 

 which has been interpreted above. A knowledge of the structure of the cell is here 

 presupposed. 



The sorts of cellular tissue are the Epidermis with its individual components, 

 the Parenchyma with its subdivisions, and the Cork. 



These are distinguished in the first place by their structure, further by the 

 form, arrangement, and mutual connexion of their cells. 



In earlier periods of vegetable anatomy the form both of the cells, and of the 

 tissue elements, which are not here included under the term, was exclusively or par- 

 ticularly regarded, and according to it were distinguished two main categories of 

 cellular tissue (or of tissues generally) ; Parenchyma, parenchymatous tissue with cells 

 that is, elements (parenchymatous cells) of nearly isodiametric form ; and Prosen- 

 chyma, Pleurenchyma with particularly long elements, which are connected with one 

 another laterally, and with their obliquely tapered or spindle-pointed ends (Prosen- 

 chymatous cells). Among the former were distinguished a number of subordinate 

 forms according to the special shape, as, Merenchyma, tabular, and stellate paren- 

 chyma, &c., the detailed enumeration of which would now be purposeless \ 



One may, as is often the case, retain these names to indicate the forms; however 

 it may be better to choose for these forms purely descriptive terms as wanted, and 

 from this point of view to term the two above-named main categories of form on 

 the one hand isodiametric cells, on the other elongated or fibrous cells. 



With reference to the structure of the cells, besides the special properties 

 according to which the distinctions between them will hereafter be drawn, a difference 



' Compare Meyen's Phytotomie, and Mohl, V.egetab. Zelle, p. i6. 



