332 



THE MICROSCOPE. 



To return to cell- development j 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 > P as ^g on to the for- 

 mation of branched cellular 



,. 7 T> 111 



tissue, o. Remarkable speci- 

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

 No. 1 9, the circular elongated cells from the Mushroom ; 

 only another and more closely connected growth of inuce- 

 dinous fungi, commonly called mushroom spawn. 



nai shape of ceils. 2, A vertical 



section of elongated cell. 



