62 GERMINAL SELECTION. 



for example, in the simultaneous rise of instincts and 

 protective similarities, or in the harmonious and 

 simultaneous augmentation of two co-operant but in- 

 dependent organs, as of the eye and of the centre of 

 vision, or of the nerve and its muscle, etc. 



The "secret law," of which Wolff prophetically 

 f speaks in his criticism of selection, is in all likeli- 

 1 hood naught else than germinal selection. This it is 

 that brings it about that the necessary variations are 

 always present, that symmetrical parts, for example, 

 the two eyes, usually v^ry alike, but under circum- 

 stances may vary differently, for example, the two 

 visual halves of soles; that homodynamic parts, (for 

 instance, the member-pairs of Arthropoda,) have fre- 

 quently varied alike, and not infrequently and in con- 

 formity with the needs of the animal, have varied dif- 

 ferently. It brings it about also that conversely species 

 of quite different fundamental constitutions occasion- 

 ally vary alike, as instances of mimicry and numerous 

 other cases of convergence show us. As soon as utility 

 itself is supposed to exercise a determinative influence 

 on the direction of variation, we get an insight into 

 the entire process and into much else besides that has 

 'hitlierto been regarded as a stumbling-block to the 

 theory of selection, and which did indeed present diffi- 

 culties that for the moment were insuperable — as, 

 for example, the like-directed variation of a large 

 number of already existing similar parts, seen in the 

 origin of .feathers from the scales of reptiles. The 

 utility in the last-mentioned instance consisted, not in 

 the transformation of one or two, but of all the scales ; 

 consequently the line of variation of all the scales must 

 have been started simultaneously in the same direction. 

 A large part of the objections to the theory of selection 



