Organic Nature s Riddle ^iZl 



are the actions- of true reproduction, and they come before 

 us naturally here, since a consideration of the process of 

 remedial reproduction in the individual, naturally leads us 

 on to the consideration of the reproduction of the species 

 itself. In the cases of the frog and the butterfly, every one 

 knows that the creature which comes forth from the Qgg is 

 very different from the parent. Animals, in fact, mostly 

 attain their adult condition by passing through a series of 

 developmental changes ; only as a rule that series is not 

 abruptly interrupted by plainly marked pauses, as it is in 

 the frog and butterfly, and, therefore, such changes, instead 

 of being obvious, are only to be detected with difiiculty and 

 through patient research. Almost every animal thus goes 

 through a series of very remarkable changes during its 

 individual process of development, or, as it is called, during 

 its ' ontogeny.' This process, in its perfect unconsciousness, 

 is like reflex action, but it is far more wonderful, since in 

 the earliest stages even nerve-tissue is absent and has itself 

 to be formed. In the accuracy of its direction towards a 

 useful end, it is the very counterpart of the most developed 

 instinct ; nor, if the impulses by which adult individuals are 

 led to seek and to perform those processes which give rise 

 to the embryo are to be called instinctive, is it easy to see 

 how the analogical use of the term ' instinctive ' can be 

 refused to that impulse by which each developing embryo 

 is led to go through those processes which give rise to 

 the adult. The action of each organism during its individual 

 development may be compared, and has evidently much 

 affinity with, the processes of nutrition and the repair and 

 reproduction of parts lost through some injury. These 

 processes of nutrition and repair have also evidently a close 

 relation to reflex action, and reflex action has also a close 

 affinity to instinctive action. Instead, however, of explain- 

 ing ' instinct ' by ' reflex action,' I would rather explain reflex 



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