6$ Prof. Meyen*s Report of the Progress of 



composition of the young ligneous layer have been published, 

 the results of which I cannot exactly determine; we shall 

 however notice this more fully after the publication of the en- 

 tire memoir. 



Corda* has published a general treatise on the stem of 

 plants : ^' the work," says the author, " was written in the year 

 18iJ3, and laid before the Royal Academy of Sciences of 

 Berlin in the beginning of 1834. It originated from MohPs 

 splendid work on palms, and from the truths disclosed in this, 

 compared with my previously (!) made observations." Corda 

 received from the Royal Society of Berlin the honourable 

 request to demonstrate how, and in what manner, palms and 

 the plants related to them grewf . In order to solve this ques- 

 tion Corda proposed to himself a series of problems, which he 

 has endeavoured to answer one after the other in the present 

 memoir. For the solution of the first question, whether the 

 externally evident formations and anomalies of the stem are 

 continued towards the interior, or whether and how the inner 

 condition exercises any influence on the formation of the ex- 

 ternal form ; Corda treats of the growth of Coniferce, Cycadece^ 

 and ferns, etc. He compares the ligneous body in very dif- 

 ferent anamorphoses of the dicotyledonous stem, and also 

 finds that it agrees in structure. Corda does well in re- 

 marking how in Cactus RogeniX a ligneous cylinder originates 

 from a blending of the ligneous bundles, similar to that in the 

 stems of arborescent ferns, which was fully mentioned in our 

 last year's report. Corda thinks he is able to say of Pelargo- 

 nium zonale, that the ligneous body of the youngest branches 

 is similarly constructed to that of the herbaceous ferns, that of 

 the older branches to that of firs, and that of the basis of the 

 stem to that of deciduous trees. I would however here ob- 

 serve, that the ligneous body in young coniferous stems, or in 

 young branches of these plants, is circumstanced exactly as in 

 the young branches of Pelargonium ; for the single ligneous 

 bundles stand in both perfectly separate. Corda, after having 

 referred in Dracana^ Elais and other palms to a ligneous cy- 

 linder similar to that in Coiiifera, formed by a blending of 

 the ends of the ligneous bundles, answers the first question 

 negatively. 



The second question, whether all forms of vegetation can 

 occur in one and the same plant, Corda answers quite as we 

 should expect, and shows that in all plants a peripherical and 



* On the structure of the vegetable Stem. Prague, 583G. 



f In our last volume, p. 553, will be found a notice of some experiments, 

 to ascertain the internal structure of the wood of palms, by Mr. Gardner. 

 — Edit. 



I It takes place in all woody Cactecs, Meyen. 



