44 CALIFORNIA ACADEMY OF SCIENCES. 



out that Mr. Spencer's investigations have here failed to 

 exhibit the crucial proof of disuse as a reducing cause, 

 which he assigns to them; it is not true that in this case 

 disuse ' remains as the only conceivable cause.' "* 



The third argument, as Romanes asserts, is too theo- 

 retical to be considered as a proof, but the second, in 

 regard to the correlation of parts of the organism is of 

 great importance, and, according to the opinion of 

 Romanes, ' ' virtually proves the truth of the Lamarckian 

 assumption." 



So important is this particular case that it is worthy 

 of a somewhat extended consideration. Spencer takes 

 the giraffe as illustrative of his point. He calls atten- 

 tion to a statement of Darwin's that " the prolonged 

 use of all the parts together with inheritance will have 

 aided in an important manner in their co-ordination." 

 " A remark," observes Spencer, " probably having 

 reference chiefly to the increased massiveness of the 

 lower part of the neck; the increased size and strength 

 of the thorax required to bear the additional burden, 

 and the increased strength of the fore legs required to 

 carry the greater weight of both. But now I think that 

 further consideration suggests the belief that the en- 

 tailed modifications are much more numerous and re- 

 mote than at first appears; and that the greater part of 

 these are such as cannot be ascribed in any degree to the 

 selection of favorable variations but must be ascribed 

 exclusively to the inherited effects of changed func- 

 tions." Mr. Spencer then describes the mechanism of 

 locomotion in the giraffe, the short hind limbs which 

 must keep pace with the long fore limbs, and the con- 

 sequent complex series of changes of bones, muscles and 

 nerves which must have taken place in order to bring 



"■' 1. c. p, 405. 



