372 MORPHOLOGY. 



of the germinal cavity corresponds to the pedicel ; the border of it is the 

 undeveloped internode between the inner and outer circles of floral en- 

 velopes in Orchis and Stylidium (in Aristolochia only one circle exists). 

 The outer surface of the hollow columella corresponds, in all these, to 

 the developed internode between the inner floral envelopes and the 

 stamen, such as occurs, for instance, in Passiflora ; the border of the 

 columella is the undeveloped internode between stamens and carpels, and 

 the inner surface of the columella is the lower part destitute of seed- 

 buds, of the central spermophore, as it occurs in some measure in the 

 Primulacece. In the same way the history of development leads to the 

 conclusion that the germen of Passiflora is a stem-organ, since the 

 cavity of the germen is indicated before the stamens show themselves, 

 and exists, distinctly formed, before the appearance of the carpels. (See 

 Plate IV., with the explanation.) 



Less easy and certain is the decision of the question of the origin of 

 the stem-pistil ; especially difficult must it be to become accustomed to 

 regard it in this point of view, to those who are still trammelled by the 

 common prejudice set up without any investigation, and therefore wholly 

 unfounded, that every pistil must be formed of carpels. When a con- 

 viction has been arrived at of the correctness of the preceding expo- 

 sition, and it is seen that even here, in the inferior germen, the most 

 essential part, the germen, is always, and the style often, formed out of 

 axial organs, the notion will be more readily accepted that the superior 

 pistil may also possibly be wholly composed of axial organs. The fol- 

 lowing axioms will serve as a point of departure : Axis and leaf are not 

 distinguishable by any difference of external form, but by their peculiar 

 process of development ; in the leaf the apex is formed first, the base 

 last ; in the axis the contrary is the universal rule. That which regu- 

 larly produces normal buds is not a leaf but an axial organ. Obser- 

 vation gives us the following facts : In some pistils, for instance, in 

 Cruciferce and Fumariacece *, the stigma is perfected first, then the style, 

 next the germen, and last of all in this, on special organs distinct from 

 the carpels, the seed-buds ; in others, as in the Leguminosa, the Liliacece, 

 the germen is formed first, and in this the seed-buds, on the borders of 

 the plates, appearing like carpels ; then the style grows up ; and at the 

 very last the apex developes into the peculiar form of the stigma. If 

 we apply to this the criterion which we have for the distinction of stem 

 and leaf, the first mode of development corresponds to a foliar, and 

 the last to an axial, organ ; and so long as a logical consistency is re- 

 garded as the only means to maintain the secure advance of science 

 against mere playing with words, we must, in the present condition of 

 observation, regard the pistils in question as formed from axial organs. 

 Probably very many families belong here, especially the Ranunculacece, 

 on which, in the absence of complete investigation, I will not venture to 

 judge. The most interesting deviation from the structure, hitherto 

 regarded as normal, occurs in a plant, Siphonodon celastrineus, described 



* Especially adapted, on account of their remarkably formed stigma. 



anthial leaves (half removed) ; c, stamens ; e, seed-buds ; x, stigma. The shaded 

 portion is the axial organ, and up to the point of junction of a and b constitutes the 

 inferior germen : above this, at first an androphore, then a gynophore. The carpels, 

 however, are wholly abortive ; and the axial organ itself forms the style, with the two 

 last-named parts above a and b. 



