Vegetable Physiology for the Year 1836. 6S 



terminal vegetation takes place. This however was known to 

 Mohl, since he represented i\ievegetatio terminalis as different 

 from the vegetatio 2^sripherica ; and he took these ideas quite 

 in a different sense from that indicated by Corda ; Mohl ap- 

 peared merely to err in so far as he ascribed only a vegetatio 

 terminalis to the Cycadece, whilst they are circumstanced ex- 

 actly as the ConifercE, 



The third question, what relation does the shoot of one year 

 bear to the stem of many years' growth, and the fourth question, 

 whether all annual and perennial plants of the same class grow 

 similarly, have found their answer in the preceding ones. 



The fifth question, whether all exogenous or peripherically 

 growing plants push forth the new-formed parts like new 

 plants, between the liber and the ligneous layer of the older, 

 is treated very fully, and the answer is: " All plants growing 

 peripherically push forth their new parts in a fissure of the 

 liber, and never between the liber and the wood ; the side of 

 the liber (the inner side of the fissure) produces new liber ; 

 whilst a part of the old liber becomes actually part of the 

 wood, and produces new wood on its exterior side." In re- 

 gard to this statement, I would refer only to the demonstra- 

 tions of some celebrated phytotomists, that the structure of 

 the cells of the liber and that of the cells of the wood is very 

 different, and that hence alone this position falls to the ground, 

 whilst it can be positively refuted in various other ways. 



The sixth question? whether the young stem or part thereof 

 grows differently from the old ; and the seventh, whether and 

 how the terminal vegetation of Mohl exists and goes on, are 

 also answered in the first replies; yet the eighth question, 

 whether a consistent and universally applicable distinction 

 of the vegetation of monocotyledonous and dicotyledonous 

 plants can be demonstrated, is answered negatively; 



The ninth question. How do mosses, lichens, algae, and 

 fungi grow, and can the above questions be in any degree ap- 

 plied to them, has also been previously answered in part ; and 

 Corda remarks, that every new cell is formed at the exterior 

 surface of the older ones, which, however, as I have in the 

 beginning of the present memoir explained, is not correct. 

 Finally, Corda has formed thirty conclusions, which he offers 

 to physiologists for their opinion and critical examination. I 

 will here only mention those which differ from the present 

 prevalent views, as, 



1. All wood must be formed in a parenchymatous tissue, 

 which tissue is separated, by means of the originating ligneous 

 mass, into two parts, at first alike, subsequently of an opposite 

 nature, the interior one of which we call wood, the external 

 one cortex. 



