VASCULAR TEXTURE. 



Fig. 91. 



141 



1st. Cellular tex- 

 ture, (Fig. 91, a,) 

 according to the opin- 

 ion of Mirbel, is com- 

 posed of a mass of 

 little hexagonal cells, 

 resembling honey 

 comb. Another 

 French botanist* 

 compares the ap- 

 pearance of the cel- 

 lular texture to the 

 froth of fermenting liquor ; he considers that each cell is dis- 

 connected with the others ; while Mirbel believes that the 

 divisions of the membrane which forms these cells, are common 

 to contiguous cells. The cellular system in animals contains 

 the fat ; in vegetables it is generally filled with resinous, oily, 

 or saccharine juices. In some cases the cells contain air only. 

 They are usually marked by small dots (See 'the dots at a, 

 Fig. 91) ; these are supposed to be apertures, through which 

 fluids are transmitted from one cell to another. 



The cellular texture composes most of the pith, parenchyma 

 and cotyledons of almost all vegetables. It is abundant in tu- 

 berous roots, pulpy and fleshy fruits, and the stems of grasses, 

 and constitutes the principal parts of mushrooms and other 

 cryptogamous plants. In the bark of plants, the cellular tex- 

 ture is situated under the cuticle ; it is filled with a juice which 

 varies in colour in different species of plants, but is most com- 

 monly green ; it gives its colour to the bark, as the same tex- 

 ture under the human cutiele gives colour to the skin. The 

 green colour of leaves is caused by the cellular texture, which 

 is inclosed on both sides by the cuticle. In the pith of young 

 plants, the cells are filled with watery fluids, but in older 

 plants they are empty or only filled by air. 



The petals of flowers owe their beautiful hues to the pres. 

 ence of cellular texture, filled with juices, which refract and 

 reflect the rays of light, in a peculiar manner. 



Vascular^ texture, consists of tubes which like the vessels of 

 the animal frame are capable of transmitting fluids. These 

 tubes are open at both ends, and are protected by a thick coat- 

 ing of cellular integument ; their sides are thick and little trans- 



* Dutrochet. 



tThe term vascular is derived from the Latin word vasculum, a little vessel. 



Cellular texture how situated Cause of the green colour of plants Beau- 

 tiful hues of petals Vascular texture. 



