PIIANEROGAMIA : AXIAL ORGANS. 227 



and the margin ; thus the lowest flowers in the Fig are the youngest, 

 like the innermost in Helianthus, the uppermost in Anthemis : equally 

 are the lowest carpels in the fruit of the Rose the youngest foliar-organs ; 

 the petals and calyx standing on the margin, the oldest. In the same 

 way, lastly, the lowest carpels in the Pomegranate stand organically higher 

 on the axis than the upper and larger carpels. One must not let the 

 contradiction between the geometrical definitions of space and the organic 

 relations lead us into error ; but get a clear apprehension of this pecu- 

 liarity. Only too readily are many authors to be noticed to whom this 

 relation has never become clear ; and thus, much else in the inflores- 

 cence and structure of blossoms remains to them obscure, and as a strange 

 peculiarity, which a more correct apprehension renders very simple and 

 natural. I shall have to enter more specially into this hereafter, when 

 speaking of the blossom. This condition occurs, indeed, most strikingly 

 in the internodes in the vicinity of the floral organs, but by no means 

 exclusively, for it appears also earlier, as in Melocactus, JSchinocactus, 

 Mammillaria, &c., where the end of the axis exhibits an infundibuliform, 

 or a cup-like form, and the terminal bud stands at the bottom of it, much 

 lower than the ten or more preceding internodes. 



II. In the second stage above distinguished, the equal expansion, in 

 all directions, of the cells formed in the preceding stage, can alone act, 

 since, still wholly imbued with moisture, the cells must be nourished 

 tolerably equally on all sides. In this period, therefore, the volume may 

 indeed alter, but not the form or relation. 



III. In the third stage, lastly, the expansion of the existing cells is 

 exclusively for the purpose of giving form. For the most part, indeed, 

 expansion of the cells according to their kind is conditioned by the 

 first formation in the first stage ( 78.), since the cells become most 

 intimately united in the directions in which they were in contact in the 

 mother-cell ; therefore, in other directions they are more loosely connected 

 and afford less facility to the passage of sap, and consequently to nu- 

 trition. Certainly, so far as our yet imperfect observations reach, it is 

 especially only the elongation of cells in the direction of the axis which 

 essentially conditions and produces the form of the developed internodes ; 

 especially, therefore, do we find it connected with the conditions men- 

 tioned in A as existing in the first stage. If we measure the length of 

 the cells in an internode (e. g., in Arundo Donax) which has just en- 

 tered the third stage, and afterwards the length of the cells in a full- 

 grown internode, we find at once that the expansion of the cells is quite 

 sufficient to account for the elongation of the whole internode. Since, 

 however, the cells enlarge unequally, we must only measure those in the 

 middle ; the result would be two small in the upper cells, and two great 

 in the lower. The former expand less, and cease sooner ; the latter, on 

 the contrary, elongate more powerfully, and continue for a longer time to 

 enlarge in the direction of their length : hence the so unfounded notion 

 of many, that the internodes grow lor a longer time at the lower end 

 than at the upper. 



All that is brought forward and enlarged upon in these paragraphs 

 relates, of course, principally to the formation of the axis of the simple 

 plants (of the second order), in which all the conditions described can 

 actually occur in nature ; it has also its application to those simple plants 

 which originate as buds upon another, whether these become detached 

 and continue to grow, or, remaining, form a compound plant with that on 

 which they have been produced. Here again it is seen, that, as in the 



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