44 



SCIENCE. 



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



US, and not with theoretical assumptions 

 and far-reaching phylogenetic hypotheses. 

 The theory of mutations formulated by 

 de Vries with such brilliant results is the 

 result of this kind of patient and step-by- 

 step observation of the now living plant 

 world. The observations of de Vries show 

 us that specific characters arise not through 

 the accumulation of useful variations, but 

 by leaps, and have nothing at all to do with 

 direct adaptation. Such as are disadvan- 

 tageous in the struggle for existence are 

 weeded out. But selection can not effect 

 the origin of specific or organization char- 

 acters as such, and this makes it clear to 

 us why — from the human standpoint — one 

 and the same problem may be solved in 

 such different fashions. 



The mutation theory of de Vries limits 

 itself to that alone which the observation of 

 the present moment can come at, to the 

 origin of the so-called 'minor species.' But 

 how the division of the plant kingdom into 

 the larger groups has come about, how it 

 has happened that the 'archetypes' have 

 reached such marked development and 

 others have died out or remained in abey- 

 ance, are further problems, the solution of 

 which may not so soon be looked for. For 

 this, however, the more intimate knowledge 

 of the factors which regulate the develop- 

 ment of the individual from the egg cell to 

 the ripening of the fruit, forms a funda- 

 mental starting point. For this purpose 

 plants are especially suitable, since, on the 

 one hand, because of the possession of a 

 punctum vegetationis, they are in later 

 life also provided with embryonal tissue, 

 and, on the other hand, because in their 

 form they are more exposed to the influ- 

 ence of the outside world than the majority 

 of animals. 



An especially important means in order 

 to the causal study of development has the 

 research into those phenomena proved it- 

 self, which we designate the regeneration 



of new formations as the result of wound- 

 ing. The questions : what really takes 

 place when an embryonic cell becomes a 

 permanent cell; the reciprocal influences 

 o£ separate plant organs, which we call 

 correlation; further the problem of polar- 

 ity; stand out wdth great clearness in the 

 phenomena of regeneration, I can, how- 

 ever, at this moment only indicate the 

 problems, and can not point out the steps 

 which have been taken toward their solu- 

 tion. A wide vista spreads out before us. 

 The more must we wonder that of the 

 countless botanical papers which appear 

 each year not more than perhaps a dozen 

 are concerned with the problem of devel- 

 opment. 



Summing up this brief presentation, it 

 should have been shown that morphology, 

 which originally formed a part of taxon- 

 omy, then grew apart from it as an inde- 

 pendent discipline. Only when it gives up 

 this separate position will morphology take 

 on new life, for such a position is war- 

 ranted only historically and not in the 

 facts. 



The earlier morphologists would have 

 said that morphology has as little to do 

 with the physiology as with the anatomy 

 of plants, which latter, at the time when 

 systematic botany was in the ascendant, 

 they reckoned also as physiology. For 

 physiology was then everything which was 

 not taxonomy. Nowadays it would be 

 carrying coals to Newcastle to point out 

 the significance of the cell doctrine for 

 morphology. For the understanding of 

 alternation of generations, of inheritance 

 and other phenomena fundamentally im- 

 portant to morphology the doctrine of the 

 cell has become of basic significance. The 

 same is true in a higher degree for the rela- 

 tion between morphology and physiology, 

 for all other tasks of the descriptive natural 

 sciences are, after all, only preliminary at- 

 tempts at orientation, which at length lead 



