MODERN BIOLOGY 577 



are rejected; it is thus definitely declared that cell-division is a physiological 

 process and not merely a question of increased superficial distention within 

 the cell, as mechanistically inclined investigators have tried to explain the 

 phenomenon. Generally speaking, clear traces of PfefTer's influence as re- 

 gards the presentation of problems and general points of view are also to 

 be found in experimental zoology, a fact, indeed, that some of its exponents 

 have openly acknowledged. His labours have proved of still greater impor- 

 tance to botanical specialized research-work; he is generally acknowledged 

 as one of the leading personalities in botany in modern times. 



Another eminent pupil of Sachs was Karl Eberhard Goebel (born in 

 1855), "^^° ^^^^ ^^ ^^^ '-^'^^ ^^ assistant at Wiirzburg and has since worked 

 as a professor at several universities, latterly at Munich. He is an investi- 

 gator of many parts, being a plant-geographist with a wide experience of 

 the tropics, a morphologist, and a physiologist. As a morphologist he has 

 always maintained the dependence of form upon function; morphology 

 should no longer be kept separate from physiology, as formerly. He employed 

 the old word "metamorphosis" to denote organic development, but not 

 in the old idealistic sense; by it he would express the idea that a change in 

 function produces a change in form. "Our idea of metamorphosis is thus in 

 the first instance ontogenetical, and thereby experimentally conceivable and 

 demonstrable," he says. According to him, no "indifferent rudiments" 

 exist, for every rudiment has its peculiar qualities, which determine its de- 

 velopment, and this can suffer change only as the result of definite changes 

 in the vital manifestations. "If we call a leaf-rudiment at any stage 'in- 

 different,' it really means nothing but a denial of the causal connexion of 

 evolutional phenomena." These changes in the conditions of life can be pro- 

 duced experimentally, and extremely important experiences in regard to the 

 organic construction of plants can be gained thereby. Space forbids our going 

 closely into Goebel's experimental studies in " Or gano graphic,'' as he calls 

 the study of the relation between an organic form and function. He has 

 hereby performed a great service in furthering the investigation of plant 

 evolution and the mechanical process in evolution in general. 



Even apart from Sachs's school there have been many important stu- 

 dents of plant biology who have produced valuable results; a couple of them 

 may be mentioned here. Julius Wiesner (i 838-191 6), professor at Vienna, 

 has carried out useful experiments in the sphere of technical botany, espe- 

 cially in regard to the effect of light upon the vegetable world, which he 

 studied in different localities and under different experimental conditions. 

 Hans Karl Albert Winkler (born in 1877), professor at Hamburg, brought 

 to light the curious graft-hybrid phenomena: as a result of grafting related 

 plant-species their tissues can be made to grow through one another in dif- 

 ferent ways. 



