46 CALIFORNIA ACADEMY OF SCIENCES. 



for innumerable chaiages and nature is not in a hurry. 

 Mr. Spencer, however, saj^s that the chances against any 

 adequate readjustments fortuitously arising must be in- 

 finity to one. But he has also shown that altered de- 

 gree of use does not cause the needed concomitant 

 variation of co-operative parts. So the chances against 

 a beneficial change in an animal must be, at a liberal 

 estimate, infinity to two. Mr. Spencer, if he has proved 

 anything, has proved that it is practically impossible 

 that the giraffe can have acquired a long neck, or the 

 elk its huge horns, or that any species has ever acquired 

 any important modification." 



Mr. Ball then draws attention to the facts which Wal- 

 lace has adduced in his recent work, "Darwinism," 

 proving that constant and independent variation is the 

 rule among all animals and plants. He then says: 

 " The lengthened wing might be gained in one genera- 

 tion, and the strengthened muscle at a subsequent pe- 

 riod ; the bird in the meanwhile drawing upon its surplus 

 energy, aided (as I would suggest) by the strengthening 

 effect of increased use in the individual." This expla- 

 nation is open to two objections: First, the one already 

 raised by Mr. Spencer, that before the second correlative 

 variation appeared the first would be lost; and, second, 

 the suggestion of Cunningham in regard to assuming 

 that use could develop the character required, but that 

 the individual thus favored could not transmit the vari- 

 ation, but that posterity must wait for the same vari- 

 ation to arise spontaneously. This hypothesis is so forced, 

 illogical and absurd, that so long as a better one can be 

 found it should be adopted. 



But one more class of evidence need be discussed, that 

 furnished by paleontology. Prof. Henry F. Osborn has 

 called special attention to this subject on two different 



