DIFFERENCE BETWEEN MEMBERS AND ORGANS. 12,g 



and their earliest states ; that, for instance, the thick scales of a bulb, the cuticular 

 appendages of many tubers, the parts of the calyx and corolla, the stamens and 

 carpels, many tendrils and prickles, &c., are, in these respects, altogether similar 

 to the green organs which have been termed simply leaves (foliage-leaves). All 

 these structures are therefore equally called leaves ; and this designation is fre- 

 quently justified by the fact that many of these organs, under peculiar conditions, 

 actually become transformed into green leaves \ Since the green organs which 

 are termed leaves in popular language (the foliage-leaves) may be considered as 

 the primary form of leaves or as leaves par excellence^ the remaining structures, 

 which are also recognised as leaf-like, are termed changed, transformed, or meta- 

 morphosed leaves. The same is also the case with those parts to which the leaves 

 are attached, and from which they grow as lateral appendages. They appear 

 sometimes as cylindrical or prismatic slender greatly elongated stems, sometimes 

 as thick roundish tubers, or are often hard and lignified (trunks). In other cases 

 they are soft and flexible, either embracing other firm bodies (bines), or firmly 

 attached to them (as in the ivy) ; they may also occur as sharp spines or as ten- 

 drils (as the grape-vine). All this is connected with the mode of life of the jjlant. 

 and with the functions of the structures under consideration. But if the one cha- 

 racteristic only is kept in view that they all bear leaves which arise below their 

 growing apices, an agreement is found as important as complete, which may for 

 the time be altogether abstracted from the physiological functions and the corre- 

 sponding structure. But when once this abstraction is made, the agreement may 

 be denoted by applying a common name to all those parts which bear leaves ; 

 they may be termed Stem-structures (Caulomes) or simply Axes. In the saitie sense 

 therefore in which, for example, the tendril of a pea is a leaf, the tuber of a potato 

 is also a stem or axial structure ; and just as the tendril of a pea is termed a meta- 

 morphosed leaf, so the tuber of a potato may also be called a metamorphosed stem. 



The same is the case with the hairs as with the leaves and axes; the distin- 

 guishing characters of root-hairs, woolly hairs, prickles, glandular hairs, &c., is that 

 they all originate as outgrowths of epidermis-cells. If we now go a step further, we 

 may term all appendages of other parts which originate as outgrowths of epidermis- 

 cells, whatever their form and function, Hairs (Trichomes). Thus the so-called palese 

 and sporangia of Ferns are trichomes ; or, if the ordinary filiform hairs are considered 

 the original form, they are then metamorphosed hairs. It does not necessarily follow 

 that the hairs grow from a true epidermis; it may be held sufficient that they arise 

 from single superficial cells ; and thus the number of the external appendages 

 termed trichomes is still further increased. 



As in the case of stems, leaves, and hairs, we may speak also of metamorphosed 

 roots ; they are usually filiform long and slender, but sometimes thick and tuberous ; 

 usually they grow beneath the ground, but also sometimes above ground, even in an 

 upward direction. Nevertheless, under all circumstances roots maintain so striking 

 a similarity to their typical forms that the term metamorphosed is but seldom ap- 

 plied to them. 



^ It was these phenomena which first called Goethe's attention to the metamorphosis of leaves : 

 at present the doctrine of metamorphosis rests on a better scientific foundation. 



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