116 THE DOCTRINE OF DESCENT. 
next, still requiring some degree of moisture, it burrows 
in the earth, and at least loves concealment, hiding with 
coquettish timidity from man and other animals. Finally, 
when the creature arrives at the surface, it hops and 
frisks, so that it carries on its existence erect, and even 
moves to and fro on two feet with marvellous rapidity. 
Transferred to completely dry land, we at last find the 
decisive influence of the airy eminence and the all- 
vivifying light. The animal is endowed with the greatest 
ease of movement; it acts and works with consummate 
skill, until a bird-like motion passes into an apparent 
flight.” 
Thus does Goethe elaborate the influence of environ- 
ment and external conditions upon the modifications of 
form ; it is in vain to look for the actual forms that are 
modified. The beaver is not transformed into the mouse- 
like burrower, the mouse into the jumping mouse, nor 
the jumping mouse into the squirrel, nor does the 
latter become a jerboa; but the “ceaseless progressive 
transformation” is perceptible only to the eye of the 
imagination. In reality, moreover, Goethe sees only 
adaptation. Greatly as he is inclined to attribute 
modifications to the effect of external conditions, he 
speaks with no less decision on the contrary side. “The 
parts of the animal, their relative form, their conditions, 
their special characters, determine the requirements of 
the creatures’ existence ;” and if within the restricted 
circle of forms, we nevertheless find that infinite modi- 
fications of form become possible (Sketch, 1796), this 
is only to be deduced fromthe individual species 
exhibited as modifications of the archetype, by Nature, 
ever one and ever creative. 
