332 



THE MICROSCOPE. 



To return to cell- development ; we found the cell chang- 

 ing in its outward forni; the transparent membranous cell 

 wall becoming thickened, and spontaneous fissure taking 

 place; and thus is formed a series of connected cells 

 variously modified and arranged, according to the conditions 

 under which they are developed and the functions which 

 they are destined to exercise. The typical form, as Ave have 



b 



Fig. 173. — a, elementary cells ; &, branched cellular tissue. 



before observed, of the vegetable cell is spheroidal ; but 

 when developed under pressure within walls, or denser 



tissues, it takes other shapes ; 

 as the ohlong, lohed, square, 

 prismatical, ci/Undrical, fusi- 

 f or 711, muriform, stellate, fila- 

 mentous, &c. : and is then 

 termed Parenchyma, and the 

 cells woven together are called 

 cellular tissue. In pulpy fruits 

 the cells may be easily separated 

 one from the other : a thin trans- 

 verse section of a strawberry is 

 represented at fig. 188, No. 15 : 

 within the cells are smaller 

 cells, commonly known as the 

 pulp. Fig. 173, a, is the ele- 

 ^^s- 174. mentary form of oval cells or 



1, A transverse section of stem of • ^ • j. j-i i? 



cao-o- vesicles, passing on to the lor- 



Equisctum, showing the hexa^ 

 nal sliape of cells. 2, A vertical 

 section of elongated cell. 



ination of branched cellular 

 tissue, h. Remarkable speci- 

 mens of the filamentous tissue maybe seen in fig. 188, 

 Ko. 19, the circular elor gated cells from the Mushroom ; 

 only another and more closely connected growth of muce- 

 dinous fungi, commonly called mushroom spawn. 



