AXIMALS A. YD THEIR ENVIRONMENTS. 305 



versa. The occurrence of this reversion of the eyes throws 

 some little light on the somewhat mechanical causes and 

 chance nature of the conditions which determine the pecu- 

 liar features and form of these fishes. How have the eyes of 

 these fishes come to be developed on one side of the body, 

 and is this condition original or acquired ? are questions 

 which the mere consideration of their peculiar structure 

 must suggest to the most casual observer. It may be said 

 that but two explanations are open for acceptation in this, as 

 in all other cases relating to the development of life at large. 

 Either we may believe that the animals were originally and 

 specially created with these peculiarities and abnormal 

 features fully developed ; or that these features are the result 

 of secondary laws and outward forces acting upon the form ; 

 and through the form, determining the "way of life" of the 

 being, to use Goethe's expressive phrase. The first hypothe- 

 sis admits of no enlargement or discussion. If accepted, it 

 must be treated as a matter of unquestioning faith around 

 which the mind may not attempt to travel. But it is exactly 

 this unquestioning belief in a theory which the scientist will 

 not recognise; and more especially if from the other view 

 of the matter, he gleans a large measure of aid in the attempt 

 to understand how the modifications before us have been 

 produced. Having due regard to the alterations and 

 changes of form and structure that are so characteristic 

 of living beings, and recognising the plasticity of life in all 

 its aspects, the zoologist will no more believe that the 

 peculiarities of the flat-fishes present us with originally 

 created features, than that the deformities in man which 

 follow the accidents of human existence, and which may be 

 transmitted like diseases from one generation to another, are 

 the products of a creative force of special kind. 



That the case of the flat-fishes has long formed a text for 

 grave biological discussion is evident from the attention it 

 has received at the hands of Mr. Spencer, Mr. St. George 

 Mivart, and other naturalists. Mr. Spencer, in dealing with 

 the modification of animal forms by the influence of external 



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