324 CONSERVATIVE ORGANS. [LECT. VII. 



are regular hexagons : in the Pear, Pyrus com- 

 munis, they resemble globular utricles : and in 

 the Rock Rose, Cistus Ledon, they are irregu- 

 lar oblong hexagons. Such are the diversities 

 of figure of these cells ; but it is still a ques- 

 tion whether the membrane of which they are 

 composed be single or double, as I formerly re- 

 marked (page 75), in describing the cellular tex- 

 ture among the general vegetable components? 

 Senebier and Link are both of opinion that each 

 cell is a separate utricle, completely distinct from 

 those which are in contact with it, and conse- 

 quently that the partitions are double on every 

 side. Link further contends * that there are no 

 visible organic pores in these partitions, the fluids 

 passing from the one to the other by a double fil- 

 tration ; and that the appearance of pores is occa- 

 sioned by small amylaceous granules scattered over 

 their surfaces. It is certainly not easy to deter- 

 mine this question as far as regards the double or 

 single nature of the cellular membrane, although 

 I am disposed to believe it is double ; both from 

 the appearance which it presents under the micro- 

 scope, and also from the greater facility which 

 such a supposition affords of explaining the origin, 

 and the hexagonal figure of the cells, a point which 

 shall be discussed in its proper place ; but, if 



* Vide ROMER, Collect. Botanic, facs. 1. p. 163. 



