64 FABRIC OF PLANTS. 



which may be described as a number of bags, bladders, 

 or vesicles, as they have been variously termed, of 

 different forms and dimensions, united together ; the 

 whole being sometimes loose and spongy, sometimes 

 close and hard, and sometimes spread out into thin 

 pellicles with scarcely a trace of the cells observable. 



M. Mirbel compares the structure of this tissue to 

 that of the froth of soap suds ; but it differs from this 

 in the partitions being always double, though Link 

 thinks the cells are originally formed, like froth, by 

 the expansion of gas. Each cell is closed all round 

 without having any inlet or pores, so far as can be 

 ascertained, though fluids certainly pass into the cells, 

 as may be seen on slightly pressing the flower cup of 

 lettuce, when a milky fluid will ooze out. The pores 

 in the cells, which M. Mirbel supposed to exist, have 

 been proved by M. Dutrochet, to be minute grains 

 sticking to the sides of the cells. 



Globular cells magnified from the leaf of Lantana acueata. 



If Link's notion of the origin of the cells be correct, 

 they must all be globular, and their various figures 

 differing from this form, must arise from the globules 



