COSMIC PHILOSOPHY 



tably involved in the destruction of the former. 

 For not only may it be forcibly argued " that 

 we can no more understand the appearance of 

 a new organism which is not the modification 

 of some already existing organism than we can 

 understand the sudden appearance of a new 

 organ which is not the modification of some 

 existing structure," but there was yet another 

 deadly weapon lying concealed amid the mass 

 of evidence with which Wolff and Von Baer 

 overthrew the preformation theory. Why this 

 roundabout method, above described, in which 

 the germs of the higher organisms are seen to 

 develop ? Why does a mammal begin to de- 

 velop as if it were going to become a fish, and 

 then, changing its course, act as if it were going 

 to become a reptile or bird, and only after much 

 delay assume the peculiar characteristics of 

 mammals ? The human embryo, for example, 

 begins with gill-like slits on each side of the 

 neck, up to which the arteries run in arching 

 branches, as in a fish ; the heart is at first a 

 simple pulsating chamber, like the heart of the 

 lowest fishes ; at a later period there is a mov- 

 able tail considerably longer than the legs ; the 

 great toe projects sideways from the foot, like 

 the toes of adult monkeys and apes ; and, dur- 

 ing the sixth month, the whole body is covered 

 very thickly with hair, extending even over the 

 face and ears, everywhere, indeed, save on the 

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