8 



CELLULAR TISSUE. 



were cut up or drawn out into threads of almost inconceivable fineness, and therefore a 

 production of membrane ; but both it and the elementary membrane are alike formed out 



of the formative fluid. Moreover, it is not regarded 

 as a substance separate from membrane, but as a 

 deposit upon one side of a pre-existent mem- 

 brane. Whenever it is found detached from 

 membrane, we must assume that the membrane 

 which supported it has been removed, or that 

 it has detached itself from the membrane. This is 

 admirably shown in Fig. 15, in which the fibre is 

 in process of being denuded by the destruction of 

 the membrane. It is usually, perhaps invariably, 

 solid, and commonly has a rounded figure. It is 

 also transparent, except in a few eases, as in 

 those of the Jungermannia, before referred to, 

 (Fig. 10.) Its use is clearly that of supporting the 

 more extended membrane, and of preventing any 

 folds of it from approximating too closely to each 

 other. 



Cellular Tissue, or Parenchyma. 

 Having now considered the "raw material" we 

 may proceed to describe the structures which 

 are produced from it. These structures are very 

 varied in appearance, and are ultimately applied 

 to very varied purposes ; but yet, in accordance with the simplicity which marks all 

 the works of God, all this may be reduced to one tissue, a structure which, in addition 

 to its being the fundamental tissue, is, in its own proper form, the most widely dis- 

 tributed of all tissues. This is termed Cellular tissue, to signify that it is made up of 



Fig. 15 Tube from the RICINUS COM. 

 MUNIS, or castor-oil plant, showing the 

 fibre at a, and the edge of the broken 

 enclosing membrane at b. Magnified 

 200 diameters.* 



i 1 Fi ;,, 16 '~ DetachedCens< Fig. 17.-Cells with Fig. 18. SAKCIXA, magnified 



a, cells of the yeast plant ( Torula cerevisia;) only two attach- 800 diameters, found in the 

 with their granular contents. ments. stomach in states of disease. 



b, the same cells in process of forming new It is a vegetable of low or- 

 cell8,a 88 eenbythebuging 8 . ganization, and resembles 



c, similar cells of the sugar plant found in . somewhat the ornament for- 

 the urine in diabetes. mer l y worn on tne breagt of 



the Jewish high-priest. It 

 consists of a mass of cells. 



hollow cases or cells. It is, moreover, that tissue which is the first found in all plants. 

 * This and a large portion of the subsequent drawings have been made from original specimens 



Others have been derived from various sources, and more particularly from the excellent lectures of 



Professor Quekett, delivered at the Royal College of Surgeons. 



