42 THE TISSUES OE PLANTS 



the entire series, a network of anastomosing vessels would 

 be the result. The capillary blood-vessels of animals seem 

 to be produced in this way, by the absorption of the con- 

 tiguous parietes of their several prolongations at the points 

 of junction, their cellular origin and original separation 

 being indicated by the persistent nuclei visible within their 

 cavities. 



Fig. 10. 



stellate cells from tlie stem of Juncus effusus, the common rush. 



But in nothing is the individuality and independency 

 of the cells so apparent, as in the varied character of their 

 contents. Generally speaking, all the cells of the same tis- 

 sue exercise the same function, and this remark applies 

 especially to those which convey fluids and air, as for, 

 instance to the fibrous tissue of the wood, and the different 

 varieties of vasiform tissue or ducts. The fibro-vascular 

 system of plants is, in fact, altogether subordinate in the 

 exercise of its functions to those cells which retain in a 

 great measure or depart but slightly from their primitive 

 form, and which are included under the general term 

 parenchyma. It is in these cells that all the organic 

 changes take place. The fibro-vascular tissue only sub- 

 serves the simple physical purpose of transmitting the 



