CHAPTER II. 



TISSUES. 



Those combinations of cells, which are produced by cell- 

 division and united to each other from the beginning of their 

 existence, are called Tissues. 



Section 1. K*[NDS OF TISSUES. 

 Each tissue may be composed either of parenchymatous 

 cells, as in the white central portion of the stem of the 

 Yamabuki, or of prosenchymatous cells with overlapping 

 ends, as in the hemp-fibres, or of vascular cells, as in the 

 minute canals in the wood of the Kiri. In the first case, 

 the tissue is known as Parenchyma (see Fig. 122) ; in the 

 second, as Prosenchyma (see Fig. 123) ; and in the last, as 

 Vascular Tissue. 



Kinds op tissues 



, Parenchyma. 

 Prosenchyma. 

 Vascular Tissue. 



The parenchyma may consist of soft parenchymatous 

 cells, as in the white central portion of the stem of the 

 Yamabuki, or of hard thick-walled parenchymatous cells, 

 as in the grit of Pears. The former kind may be called the 

 Soft Parenchyma, and the. latter the Hard Parenchyma. 



-,-. ( Soft Parenchyma. 



Parenchyma] „ , „ ' 



l .Hard Parenchyma. 



There is still another kind of parenchyma, which is composed of those 

 cells that are long and mostly prismatic with their walls thickened along 

 the longitudinal angles. It is known as Gollenchyma and is found in th9 

 stems of many plants, as the Tonasu, Shukaido, etc. 



The prosenchyma may consist of soft flexible prosen- 

 chymatous cells, as in the hemp-fibres, or of hard lignified 



