PHANEROGAMIA : AXIAL ORGANS. 223 



in such a manner that the axis readily breaks off here with smooth 

 fractured surfaces, or separates spontaneously from the plant at a 

 certain epoch, as in many flower or fruit stalks. 



Moreover, the observation ( 68.) formerly made is to be repeated 

 here, that every part of a plant is capable of development in one, 

 two, or three of the dimensions of space ; therefore, besides the long 

 and slender, and the short, thick, almost globular, axes, there may 

 be flattened, strap-shaped, or foliaceous stems. 



Finally, it must also be remarked here, that there are but very 

 few plants in which the axis is homogeneous throughout, at once in 

 form (as to a certain extent in Lemna, which consists solely of one 

 undeveloped internode) and in duration (the few perfectly annual 

 plants excepted, which form neither transitory internodes in ger- 

 mination nor flower-stalks of brief duration at a later period). 

 Most plants have heterogeneous axes, especially of such kind that 

 internodes of different form succeed each other (as in almost every 

 plant), or that the internodes differ in duration (as in the many 

 plants in which the lower internodes form a trunk, while the upper 

 remain as stem). 



If we would avoid bringing the greatest difficulty into the study of the 

 stem, we must, throughout, very carefully separate the morphology, 

 strictly so called, from the anatomy.* The mere accident, I might say, 

 that the first Palm-stems were at once studied internally as well as ex- 

 ternally, has had much influence in the science. Without any anatomy 

 at all, the trunk of Draccena is essentially distinct from that of Calamus^ 

 and the distinction is exactly of the same hind as that between the 

 trunks of Mammillaria and dEsculus. Whether and what anatomical dif- 

 ferences (besides the general distinction between Mono- and Dicotyledon, 

 which is always premised here) are connected with these essential forms, 

 are questions for subsequent inquiry. 



From the division into annual and perennial, into developed and un- 

 developed, internodes, proceed four forms, of which it is easy to find ex- 

 amples in the vegetable kingdom ; e. g. clearly developed internodes, 

 annual Cannabis, perennial ^Esculus ; clearly undeveloped internodes, 

 annual Myosurus (with the exception of the flower-stalk), perennial 

 Melocactus. It would be equally easy to find examples of the combina- 

 tion of these forms in the same plant, nay, even of all possible combina- 

 tions, which arise if we divide the annual internodes again, as above, into 

 these sections, according to their different duration. The stem of Avena 

 sativa frequently commences with a developed, speedily decaying inter- 

 node ; next follow several undeveloped internodes, becoming successively 

 broader ; then come again developed internodes.f The two last kinds endure 



* As a most striking example of a confusion of ideas, I may here mention that Meyen, 

 in the second division (vol. i. of his Physiology; the first treats of the elementary 

 organs), under the head of " General Comparative Exposition of the Types, according 

 to which the Elementary Organs are combined in the Structure of Plants," treats wholly 

 and solely of the stem ; while, from under such a head, one can only think of the 

 study of tissues, organography, natural system, &c. ; anything, in fact, but what he 

 gives. 



f The same occurs in Hordeum vulgnre. Apparently it depends, in both, on the 

 position of the grain on the surface of the earth, whether the first internode becomes 

 elongated or not. 



