COMPARED WITH THOSE OP ANIMALS. 



39 



in this case the hexagonal is the predominating form, 

 although the heptagonal, pentagonal, and cubical varieties 

 are also represented. 



Fig. 6. 



Irregular polyliedral cells from tlie pith of tlie elder. 



So also cubical cells may become rectangular four-sided 

 prisms, or even be so much compressed as to assume the 

 appearance of fibres, as is fully seen in the annexed section 

 of the rind of the common a;ourd. 



Vertical section of the rind of the gourd. 



Thus, it is evident, that cells may, to a certain extent, 

 change their form, without changing their nature or the 

 identity of their function. 



When the cells of plants are bounded by curved instead 



