»*»*.] Two Schools of Plant Physiology. 2l:i 



tion of text books. In short, this school is of a date so recent 

 that comparatively few of its theories are accessible to Un- 

 English-speaking world. As an illustration of this fact, one 

 of the most strongly contested points of disagreement between 

 Sachs and Schwendener is in reference to the cause of twining 

 stems. Vines in his text hook of physiology gives the theory 

 of Sachs and also those of various later writers, and among 

 others refers briefly to that of Schwendener in these words: 

 " Schwendener attributes the twining to circumnutation and 

 to an antidromous torsion." Professor Schwendener said of 

 this after reading it carefully, " This is quite erroneous ; he has 

 entirely misunderstood my theory. According to my expla- 

 nation of this fact, torsion is only an effect of twining and not 



In that department of plant physiology which deals with 

 nutrition there are fewer differences of opinion than in that of 

 the physiology of movement. It is in the latter field espec- 

 ially that Professor Schwendener has worked out solutions of 

 various problems differing vitally from those of any other 

 physiologists. In fact, his fondness for mechanical questions 

 has given him the reputation of a specialist in the narrow 

 sense of the term. Added to this is the fact that his discuss- 

 ions of several theories are so abstruse as to render them diffi- 

 cult even for the mature students who are likely to choose such 

 studies in the German Universities. Thus, in speaking of his 

 work on the position of leaves, he said it was extremely diffi- 

 cult for his advanced students who had been under his own 

 training to follow his lectures on this subject; that with all 

 Ids illustrations and models which he had constructed for 

 these lectures it was often necessary for him to go twice 

 through the same lecture, and that he never felt certain of the 

 number who had conquered the subject until he had tested 

 them in the laboratory. 



Again referring to Vines, w r ho may be considered at once 

 the best exponent of the views of the English botanists and 

 a fair disciple of Sachs, he says of this: "Schwendener has 

 constructed an extremely simple theory regarding the posi- 

 tion of leaves." 



