164 COMPENDIUM OF GENERAL BOTANY. 



a manner similar to the trichomes or leaves (phyllome). An un- 

 warranted procedure is to conclude that the reproductive organs are 

 evolved from the vegetative organs, or, as it is usually expressed, 

 "are derived phylogenetically." The advocates of the theory of 

 descent either take its correctness for granted or seek to make it ap- 

 plicable to this or that case. We shall refrain from going beyond 

 the conclusions based upon observed facts into the realm of phan- 

 tasy and pure speculation. Also the classification of leaves as 

 "leaf-forms" is not acceptable to those who wish to consider, for 

 example, the cataphyllary leaves as phylogenetically derived from 

 the foliage-leaves. 1 A few remarks on the '* transition " of vegeta- 

 tive leaves into reproductive organs shall now be added. 



In the first place it is evident that the stamens and foliage- 

 leaves, morphologically considered, are both leaves, yet the differ- 

 ence between them is very great when we consider each as to its 

 function in the mature state, since such a mode of treatment is 

 appropriate here as well as it was in regard to the internal organs 

 (tissue-systems). It is also clear that we cannot conceive of the ori- 

 gin of a stamen other than that it starts as a small wart-like cellular 

 protuberance on the side of the stem. Finally, it is also clear that 

 the young stamen will take such a course in its development as will 

 lead to the formation of a pollen-bearing organ rather than of 

 a foliage-leaf. The morphological conception of an organ is justifi- 

 able, but it must not be valued too highly. 



Between the involucre and starniniferous flowers of the Corn- 

 positce occur the so-called neutral flowers, which to the observer 

 seem to be formations of a double nature. It is, however, evident 

 that in the development of stamens such intermediate states are 

 not passed through ; these neutral organs can hence not be looked 

 upon as states of transition. Morphology based upon facts of de- 

 velopment points out the great similarity between stamen and leaf, 

 between most carpels with their ovules and divided or compound 

 leaves; this similarity is further emphasized by the frequent occur- 

 rence of the apparent reversion of the floral leaf to a foliage-leaf. 

 Every observer has no doubt witnessed such phenomena. But to 

 conclude that such changes are evidence of the evolution of repro- 

 ductive organs from purely vegetative leaves is wholly unwarranted ; 

 it has not been proven. 



1 WESTERMAIER, Natur und Offenbanmg, 1893. 



