212 MORPHOLOGY. 



and stem, which had been completely unfolded in the Lycopodiacece and 

 Ferns, appears to retreat again. In Equisctacece and Lycopodiacece. , 

 nature apparently drops for a time that second organ mentioned in the 

 Mosses ; here, however, there is again great want of observed facts. 



4. This is again taken up in the Rhizocarpece, and a definite physio- 

 logical function attached to it ; it becomes the seed-bud (ovule), and the 

 sporocarp the anther ; leaf and stem remain as morphologically and phy- 

 siologically distinct organs, without, however, the reproductive organs 

 being determinately divided between them (but here, again, there is great 

 want of investigation). 



5. Lastly, in the Phanerogamia nature again takes up all the separate, 

 successively evolved and gradually completed elements, and combines 

 them into a perfect plant. Leaf and stem, morphologically and, in gene- 

 ral, physiologically separated, form the entire plant. The stem is de- 

 veloped at certain points into perfect seed-buds with definite function ; 

 the leaf, in like manner, into perfect anthers ; and both become enclosed 

 in definitely modified leaves, and constitute perfect flowers. Now, how- 

 ever, but with a constant retention of the essential, a wide field is opened 

 for the development of the separate parts into varied forms, under which 

 circumstances even particular earlier stages of individual organs reappear; 

 for instance, the leafless stem, flat in Lemna, solid in Melocactus ; the 

 sporophyll of the Ferns in the Cycadacece, perhaps even the develop- 

 ment of the anther out of a stem-organ (?) in Caulinia fragilis, the stem 

 of an Equisetum with the function of a leaf in Casuarina, Ephedra, 

 Cactecs, &c. * 



I have here only insisted on the main points, in order that the survey 

 might be more easy, but there are many others which might be traced out 

 in the same manner. In the Mosses, for example, the stem originates as 

 an organ morphologically bounded at one extremity ; in the Ferns, &c., 

 morphologically limited in two directions, as stem (sensu stricto) and root ; 

 but in neither exists any relation with the two ends of the spore-tube. 

 This relation first appears in the Rhizocarpece, and in the Phanerogamia 

 it becomes so perfected that the stem, without exception, originates from 

 the penetrating, closed end of the pollen-tube, and the root from the op- 

 posite extremity. 



For the rest, I leave the special establishment of what has been stated 

 in the paragraphs to the succeeding pages, only remarking, once more, 

 that all that is said about stem and leaf, so far as it agrees with what 

 has been previously mentioned, holds good also of the rest of the 

 Gymnosporce. 



* I here expressly beg that no one will impute to me the folly of imagining that, in 

 what I have just said, I have cast a peculiarly profound glance into the mysterious 

 workshop of Nature, that I might, as indeed often happens in our days, by such an 

 assumption of wisdom establish a vain system which investigation would, perhaps, 

 to-morrow cast aside as rubbish. I have only adopted the means which, with our 

 human finite minds, we so often have recourse to in endeavouring to facilitate the 

 survey of the whole series of forms by a figurative representation. I am defended 

 against the danger of regarding it as anything more, by the healthy plainness which I 

 owe to my teacher Fries, from whose logic I have learned as much Botany as from all 

 botanical treatises put together. 



