opment of certain characters in an organism, while 

 others progress and still others become retrogressive. As 

 •a rule use and disuse are of great efficacy in this regard, 

 and conjointly with these compensation and correlation." 

 Occasionally also irregular development sets in, which pro- 

 ceeds by leaps. 



Of course, Eimer could not but in his turn burn in- 

 cense before Darwin by declaring that he would not dare 

 to cross swords with such a man, while in reality he repu- 

 diates all of Darwin's fundamental tenets. 



It may be well to state here in addition a few important 

 supplementary considerations: "Development can every- 

 where proceed in only a limited number of directions be- 

 cause the constitution, the material composition of the 

 body, conditions these directions and prevents variation in 

 all directions." This is an important statement because 

 Eimer clearly expresses therein the difference between his 

 own theory and that of Naegeli. He makes the direction 

 of development dependent on the material composition 

 of the body, whereas Naegeli considers it dependent upon 

 an internal tendency of every being to perfect itself, hence 

 upon a power inherent in the body. Elmer's view there- 

 fore tends towards a mechanical explanation, while Naegeli 

 postulates a vital energy. The "internal causes" according 

 to Eimer find their explanation in the material composition 

 of the body. Since the growth of the individual organism 

 depends on this composition and on the external influences, 

 Eimer compares family-development with it and designates 

 the latter as "organic growth." In opposition to Naegeli 



74 



