PHYSIOLOGICAL BOTANY. 219 



salt and the water by which it is dissolved. Just as in 

 this case both salt and water are contained in every 

 differential of magnitude (sit venia verbo), so is the 

 cellular matter and the water in that of the membrane ; 

 with this difference, that the membrane is never rendered 

 fluid by the water, because the latter merely dissolves a 

 definite minute quantity, and then does not take up 

 more water until the portion first taken up has been 

 removed." Now, where do the aqueous particles exist 

 in the membrane ? They cannot exist anywhere but in 

 its interstices, however minute these may be, and how- 

 ever minute the particles of the membrane may be, 

 between which the aqueous particles penetrate. Un- 

 doubtedly such interstices, which we call invisible pores, 

 must exist, unless we admit an infinite penetration of 

 the water and the membrane. Independently of the 

 fact that such penetration cannot be perceived, nor even 

 imagined, the water and membrane would then form an 

 indivisible substance. The penetration would also be 

 mere groundless hypothesis. Salt, when in solution, 

 certainly exists only in the interstices of the water; 

 soluble bodies force carbonic acid from the pores of 

 water, because they take its place themselves. Our 

 system of physics must be altogether modified, if we are 

 to deny the existence of invisible pores. Physio-philo- 

 sophy is alone capable of affording an explanation of this, 

 because, according to its theorems, all forms of matter 

 are originally the same, and the differences depend upon 

 an increase or a diminution of the cohesive attraction 

 of one for the other. Still it would be difficult to find in 

 it an explanation, where membrane and water only are con- 

 cerned, without admitting the existence of such pores. Are 

 we, then, who are accustomed to work with the micro- 

 scope, to pretend that we can see everything? Thus 

 there are different gases, none of which are visible to us, 

 and in which we must admit the existence of large inter- 

 spaces, for the explanation of the phenomena which are 

 exhibited when they are mixed with each other or with 

 aqueous vapour. That these pores are not disseminated 



