LUDWIG AND MODERN PHYSIOLOGY. 367 



own bodies, that we had internal as well as external organs, and 

 probably one of the first generalizations which arose out of this 

 knowledge was, that "if one member suffer all the members suffer 

 with it" — that all work together for the good of the whole. In earlier 

 times the good which was thus indicated was associated in men's minds 

 with human welfare exclusively. But it was eventually seen that 

 nature has no less consideration for the welfare of those of her products 

 which to us seem hideous or mischievous, than for those which we 

 regard as most useful to man or most deserving of his admiration. It 

 thus became apparent that the good in question could not be human 

 exclusively, but as regards each animal its own good — and that in the 

 organized world the existence and life of every species is brought into 

 subordination to one purpose — its own success in the struggle for 

 existence. 1 



From what has preceded it may be readily understood that in physi- 

 ology adaptation takes a more prominent place than evolution or 

 descent. In the prescientitie period adaptation was everything. The 

 observation that any structure or arrangement exhibited marks of 

 adaptation to a useful purpose was accepted, not merely as a guide in 

 research, but as a full and final explanation. Of an organism or organ 

 which j)erfectly fulfilled in its structure and working the end of its exist- 

 ence nothing further is required to be said or known. Physiologists of 

 the present day recognize as fully as their predecessors that perfection 

 of contrivance which displays itself in all living structures the more 

 exquisitely the more minutely they are examined. No one, for example, 

 has written more emphatically uonp this point than did Ludwig. In 

 one of his discourses, after showing how nature exceeds the highest 

 standard of human attainment — how she fashions, as it were, out of 

 nothing and without tools instruments of a perfection which the human 

 artificer can not reach, though provided with every suitable material — 

 wood, brass, glass, india rubber — he gives the organ of sight as a signal 

 example, referring among its other perfections to the rapidity with 

 which the eye can be fixed on numerous objects in succession and the 

 instantaneous and unconscious estimates which we are able to form of 

 the distances of objects, each estimate involving a process of arithmetic 

 which no calculating machine could effect in the time. 2 In another 



] I am aware that in thus stating the relation between adaptation and the struggle 

 for existence, I may seem to be reversing the order followed by Mr. Darwin, inas- 

 much as he regarded the survival of organisms which are fittest for their place in 

 nature, and of parts which are fittest for their place in the organism, as the agency 

 by which adaptedness is brought about. However this may be expressed it can not 

 be doubted that fitness is an essential of organisms. Living beings are the only 

 things in nature which by virtue of evolution and descent are able to adapt them- 

 selves to their surroundings. It is therefore only so far as organism (with all its 

 attributes) is presupposed, that the dependence of adaptation on survival is intelli- 

 gible. 



2 I summarize here from a very interesting lecture entitled "Leid und Freude in 

 der Naturforschung," published in the Gartenlaube (Nos. 22 and 23) in 1870. 



