THEORY OF DUTROCHET. 93 



extreme points of the fibres, in which he then 



the roots. 



located the origin of the moving force. 



The peculiar activity of the spongioles must, 

 according to DUTROCHET, be ascribed to all -the 

 causes, taken together, which determine the phe- 

 nomena of Endosmosis. 



Now that we are better acquainted with the phe- objections 



to this 



nomena of what is called Endosmosis, we may theory. 

 oppose to this view some well-founded doubts. All 

 observers agree, that the increase in volume of a 

 liquid, separated from another liquid by a porous 

 diaphragm, is determined by a difference in the 

 qualities of the two liquids. If their composition 

 and properties be the same, there is no cause suffi- 

 cient to produce mixture and change of volume, 

 since in this case, the attraction of both for the 

 diaphragm, and for each other, is perfectly equal. 



In the course of his admirable researches, BRUCKE observa- 

 determined the specific gravity of the spring sap 

 which had flowed from the vine. He found it, in 

 one plant, == 1*0008, and in another, = 1*0009. 



These numbers prove irresistibly, that the spe- 

 cific gravity of the sap of the vine is in no way 

 different from that of ordinary spring water, or of 

 the water which has filtered through garden mould. water> 

 In most cases, spring water contains even more 

 dissolved matter. 



The spring sap of the vine, which had the sp. g. Force with 

 1-0008, raised a column of mercury to the height of sap rises. 

 * Poggendorf s Annalen der Physik, Ixiii. 177. 



* f 



