332 



THE MICROBCOPE. 



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

 ing in its outward form, 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 we have 



Fig. 173. — a, elementary cells ; b, 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 oblong, lobed, square, 

 prismatical, cylindrical, fusi- 

 form, 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- 

 mentary form of oval cells or 

 vesicles, passing on to the for- 

 mation of branched cellular 

 tissue, b. Remarkable speci- 

 mens of the filamentous tissue may be seen in fig. 188, 

 No. 19, the circular elongated cells from the Mushroom ; 

 only another and more closely connected growth of muce- 

 dinous fungi, commonly called mushroom spawn. 



Fig. 174. 

 1, A transverse section of stem of 

 Equisetuvi, showing the hexago- 

 nal shape of cells. 2, A vertical 

 section of elongated cell. 



