APPENDIX. 49 



peculiar evolution, carrying with it its own de- 

 pending race of organisms. 



The fact that animals and plants at the present 

 time show such various degrees of organization is 

 also accounted for on the last supposition, for those 

 of lowlier organization are merely of more recent 

 origin and have not progressed so far in idioplasmic 

 development. 



This automatic perfecting principle has been the 

 mark of much criticism. Some have confounded it 

 with the mystical nisus formativus, or formative 

 principle of preceding theorists. But, as Weismann 

 remarks, Nageli's phyletic force is conceived as a 

 thoroughly scientific mechanical principle. Nageli 

 has simply made application in the organic world 

 of the principle of entropy, as stated in the mechan- 

 ical theory of heat. Nageli himself also compares 

 his internal perfecting principle to mechanical 

 inertia. He says, "the force of evolution once 

 started in a given direction, tends to continue in the 

 same direction. This constitutes the law of inertia 

 in the organic world." 



Two other matters remain to be noticed. The 

 first of these is Nageli's use of the German word 

 Anlage. We have been unable to give a perfectly 

 satisfactory translation of this word in its techni- 

 cal meaning. We have received some comfort, 

 though but little help, from the experience of the 

 translators of similar works. Selmar Schoenland, 

 in translating from Weismann, renders it variously 

 as "germ,'' "germ of structure," "germ (of Nag- 

 eli)," "germ of Nageli," "Nageli's preformed germ 

 of structure," "preformed germs," "tendency." 



