GROUi^DS AND CONSEQUENCES OF EVOLUTION. 349 



certain facts. We have only reached the determination 

 of a certain order of succession, and a certain derivative 

 relation. We have not yet discovered the agencies through 

 which the derivation is effected, and the conditions under 

 which those agencies are operative. Nor have we dis- 

 covered the efficioicy which operates the agencies, nor the 

 mode of its activity, nor the reason why all these things 

 are brought to pass as they are. In brief, after we have 

 discovered what takes place, it remains to learn through 

 what it takes place, and hy what it takes place, and for 

 what it takes place. These are the ulterior questions 

 which were not touched by Professor Huxley in his lect- 

 ures. He did not completely ignore them, but he waived 

 them.* 



Now, while the present occasion is not one for discuss- 

 ing these ulterior questions, it may be profitable to bring 

 them into view for the purpose of enabling the reader 

 to appreciate the vast breadth of the theme, and the sepa- 

 rate subdivisions which must be clearly recognized in 

 forming judgments about it. 



I. What are the Physical and Physiological Conditions 

 (mediate or scientific causes) of Variative Derivation? 



It is in the domain covered by this question that the 

 various theories of derivation have sprung up. At the out- 

 set a fundamental discrimination must be made. There 

 are the organic activities appropriating material within 



* He says : " The cause of that production of variations is a matter not at all 

 properly understood at present. Whether it depends upon some intricate ma- 

 chinery if I may use the phrase of the animal form itself, or whether it 

 arises through the influence of conditions upon that form is not certain, and the 

 question may for the present be left open." Pop. Sci. Monthly., No. Ivi, 210. 

 'My present business is not with the question as io how nature has originated, 

 as to the causes which have led to her origination."' Ih. Iv, 51. Our present 

 inquiry is not ivhy the objects which constitute nature came into existence, but 

 when they came into existence, and in what order. lb. Iv, 51. 



