42 



SCIENCE. 



[N. S. Vol. XXII. No. 550. 



But the historical question can not help 

 us over the ontogenetic problem any more 

 than the solution of the latter alone can 

 answer the historical question. Even if it 

 were proved in all cases that sporophylls, 

 flower leaves, sepals, etc., are transformed 

 foliage leaves, it would remain undecided 

 that these are phylogenetically older than 

 the former. This phylogenetic problem, 

 however, is with our present means and 

 knowledge not subject to solution with cer- 

 tainty, while the ontogenetic problem, on 

 the contrary, is. Problems, however, which 

 may not be solved appear to me less impor- 

 tant than those which may. 



To be sure, the solution of the onto- 

 genetic problem is hedged about with great 

 difficulties. For the results which have 

 already accrued, valuable as they may be, 

 take their importance from the fact that 

 they lay the foundation for the future.. 

 work: what changes take place during 

 transformation, and upon what outer and 

 inner conditions are they dependent ? We 

 may comfort ourselves as little as could 

 Goethe at one time with the view that 

 flowers differ from the vegetative shoot in 

 a refinement of the sap; rather would we 

 know what change of the materials, and 

 what other changes, are connected with the 

 order of successive developmental stages of 

 the flower. This, to us as good as unac- 

 quired knowledge, should give us a more 

 penetrating glance into the nature of de- 

 velopment than we have as yet had. To 

 just this purpose plants are especially 

 well adapted, for experience has shown us 

 that the development of a plant is not pro- 

 duced as is the melody in a music box, in 

 a definite order so long as the outer source 

 of power is present to start it ; for the ex- 

 periments of the last few years indicate 

 rather 'that the form relations of chloro- 

 phyll-bearing plants are not predetermined 

 in the germ cell, but in the course of de- 

 velopment.'^ As a result we can not only 

 5 Goebel, ' Flora/ 1895, p. 115. 



arrest development at any particular stage, 

 but we can also cause fundaments to unfold 

 which were previously ' latent. ' Historical 

 morphology has contented itself as regards 

 the unfolding of latent fundaments also 

 with an historical explanation of the facts. 

 The observation, e. g., that instead of the 

 seed scale of the Abietineae under certain 

 circumstances an axillary shoot appears, 

 has been used by prominent botanists to 

 support the conclusion that the seed scale 

 has arisen phylogenetically from a shoot. 

 Such an hypothesis would get beyond the 

 rank of pure supposition if a living or 

 fossil form certainly related to the Abie- 

 tineae could be pointed out, the cones of 

 which bear in the axils of the cover scales 

 shoots possessed. of macrosporophylls. As 

 long as such proof is not forthcorning, we 

 stand opposed to a phylogenetic explana- 

 tion of this observation 'kuehl bis ans Herz 

 hinan.' We seek rather to establish the 

 conditions under which the fundaments, 

 which otherwise become seed scales, develop 

 into shoots, and hold before us therewith 

 the possibility that the forebears of the 

 Abietineae could have borne their ovules 

 upon axillary outgrowth of the cover scales, 

 which, indeed, possessed the ability under 

 certain circumstances which disturbed the 

 normal development to form shoots, but 

 which phylogenetically does not need to 

 have been at any time an axillary shoot. 



The question of the significance of meta- 

 morphosis leads us into another field of 

 morphology. The above-cited examples 

 show that the transformation of organs 

 always goes on hand in hand with a change 

 of function. This gives us the occasion to 

 take up a further problem of modern mor- 

 phology: the relation between form and 

 function. The old morphology believed 

 that it should keep away from this ques- 

 tion because it held that the function of 

 an organ had nothing to do with its 'mor- 

 phological meaning.' Just recently we 



