VARIOUS FORMS OF CELLULAR TISSUE. 



389 



Fig. 199. 

 C3\ 



Section of Cellular parenchyma of Rush. 



Fig. 200. 



air-spaces. In other instances these air-spaces are large cavities 

 which are altogether left void of tissue : such is the case in the 

 Nuphar lutea (Yellow water-lily), the Footstalks of whose leaves 

 contain large air-chambers, the walls of which are built up of very 



regular cubical cells, 

 whilst some curiously 

 formed large stellate 

 cells project into the 

 cavity which they bound 

 (Fig. 200). The dimen- 

 sions of the component 

 vesicles of Cellular tissue 

 are extremely variable ; 

 for although their dia- 

 meter is very commonly 

 between l-300th and. 

 1 -500th of an inch, they 

 occasionally measure as 

 much as l-30th of an 

 inch across, whilst in 

 other instances they are 

 not more than 1-3-0 00th. 

 285. The component 

 cells of Cellular tissue 

 are usually held to- 

 gether by an intercel- 

 lular substance, which 

 may be considered an- 

 alogous to the 'gela- 

 tinous ' layer that inter- 

 venes between the cells 

 of the Algas. There 

 are many cellular sub- 

 stances, however, in 

 which, in consequence 

 of the loose aggrega- 

 tion of their compon- 

 ent cells, these may be 

 readily isolated, so as 

 to be prepared for sepa- 

 rate examination with- 

 out the use of Reagents 

 which alter their condi- 

 tion : this is the case with 

 the pulp of ripe Fruits, 

 such as the Strawberry or Currant (the Snowberry is a particularly 

 favourable subject for this kind of examination), and with the 

 parenchyma of many fleshy Leaves, such as those of the Carnation 

 (Dianthus caryophyllus) or the London Pride (Saodfraga crasd- 



Cubical parenchyma, with stellate cells, from 

 petiole of Nuphar lutea. 



