178 COMPENDIUM OF GENERAL BOTANY. 



recurring morphological relations. With this statement I draw 

 only one deduction from the investigations of Schwendener and his 

 pupils. This is done in order to meet the superficial conclusions of 

 some scientists, that the newer scientific teaching in regard to 

 phyllotaxy does not leave a trace of the idealistic (in the author's 

 sense) in the plant creation. 



True and rational idealism is not at all disturbed by such mate- 

 rialism. The academic speech of du Bois-Retmond (Berlin, July 8, 

 1880) had only an oratorical value when he stated that Schwen- 

 dener could pride himself as being one of those investigators who 

 had aided in driving the "misty forms of vitalism " out of their 

 " last hiding-place." The great fame of Schwendener is due to his 

 achievements in the domain of pure scientific teleology. His au- 

 thority as a botanist has been recognized for years, and will no 

 doubt stand for many years to come. 



In this problem of phyllotaxy repeated attempts have been 

 made to give a teleological explanation,' but the real progress, which 

 we owe to Schwendener, has been made with reference to another 

 branch of our science. 



The advance made evidently lies in that we can say : that me- 

 chanical relations — contact- and pressure-effects — are the immediate 

 causes for the appearance of the divergences. However, there are 

 many problems still unsolved. Why do certain plant-groups (mono- 

 cotyledons, dicotyledons, gymnosperms) produce as a " basis " one 

 cotyledon with alternating leaves, or two equally large, or three to 

 eight nearly equally large cotyledons? Further, why does the 

 gradual reduction in the size of the organs not appear regularly in 

 plants where the divergence is approximately f ? Why are vascular 

 bundles (leaf-trace bundles) so united laterally that they must 

 produce certain tensions at suitable periods? These and similar 

 questions are still unanswered. We must admit that the chief 

 merit of Schwendener's (in part also of Hof meister's) discoveries lies 

 in the fact that he has refuted the spiral theory, and in the intro- 

 duction of mechanical factors into the domain of morphology. 

 ScHiMPER, Braun, as well as the Beavais and Naumann brothers 

 looked upon lateral growth, especially the leaf-formations, as always 

 following certain lines. There can be no genetic significance at- 

 tached to the ground-spiral, nor to the secondary spirals or " par- 



^ Depending upon iidaptation to light and space. 



