14 GENERAL TEXTURE OF PLANTS - . 



foundations physiologists have, at their plea- 

 sure, constructed various theories, relative 

 to the motion of the sap, respiration and other 

 functions, presumed to be analogous to those 

 of animals. The anatomical observations of 

 Mirbel go further than those of Grew, &c.* 

 and it is necessary to give a short account of 

 his discoveries. 



He finds, by the help of the highest mag- 

 nifying powers, that the vegetable body is a 

 continued mass of tubes and cells; the former 

 extended indefinitely, the latter frequently 

 and regularly interrupted by transverse par- 

 titions. These partitions being ranged alter- 

 nately in the corresponding cells, and each 

 cell increasing somewhat in diameter after its 

 first formation, except where restrained by 

 the transverse partitions, seems to account 

 for their hexagonal figure*. See Tab. \.f. a. 

 The membranous sides of all these cells and 

 tubes are very thin, more or less transparent, 

 often porous, variously perforated or torn. 

 Of the tubes, some are without any lateral per- 

 forations, f. b, at least for a considerable ex- 



m 



* In microscopic figures they are generally drawn 

 like circles intersecting each other. 



