5/i VEGETABLE ORGANOGRAPHY. 



resolve, in order to understand the use of the vessels, 

 but it is unfortunately one of the most diiScult parts of 

 the subject. It may be divided into two — the termina- 

 tion of vessels, and theii juxtaposition. 



We have said, in speaking of the Trachege in par- 

 ticular, that some think that they are lost in the Cellular 

 Tissue, and others, that they go to meet the pores of the 

 Stomata. These two opinions can be sustained in all 

 kinds of vessels except in the strangulated, which are 

 limited to the articulations ; but no one has hitherto 

 seen in a clear manner either the origin or the termina- 

 tion of a vessel, and this is a point to which it is im- 

 portant to call the attention of observers. 



As to the position of the vessels in the tissue, it is 

 certain that they are always surrounded by elongated 

 cellules usually close to one another. But have they 

 any communication with the intercellular passages ? Do 

 the walls of the cellules themselves bear any part in the 

 construction of the different kinds of vessels ? These 

 questions appear to me to be still without a precise 

 answer. 



Section VIII. 

 On the Use of the Vessels. 



If we are far from agreeing upon the structure of the 

 vessels of plants, we must expect to find still more 

 difference, if possible, in the opinions relative to the use 

 of these organs. 



The only point upon which observers are agreed, is 

 that the vessels do not contain any Proper Juice. Kieser 



