THE REAL DIFFICULTY 205 



natural proportions of the sexes. The immature reproductive 

 organs, while in a state of " sexual indifference," were biassed 

 towards femaleness. Thus the case does not do more than show 

 that the gonads are reachable by somatic influences, which no 

 biologist has ever denied. 



The Real DiflBculty. — Even when we recognise, as fully as we 

 can, the unit}^ of the organism, that each part shares in the life 

 of the whole, it is very difficult to think of any modus operandi 

 whereby a local modification can specifically affect the germ- 

 plasm. The argument that we can as little understand the 

 modus operandi whereby an influence passes from the gonads 

 to distant parts of the body is not really sound. For we know 

 that in some cases the reproductive organs, besides being areas 

 for the multiplication of germ-cells, are organs of internal secre- 

 tion, producing specific substances which are carried away by 

 the blood-stream, and serve as the stimuli awakening the dormant 

 potentialities of distant parts. 



Nor does the fact that morbid processes in a particular part 

 may result in a diffusion of toxins, which saturate even the germ- 

 cells, help us much in our attempt to picture how a modification 

 could become transmissible. For there is not the slightest 

 reason for supposing that the ordinary modifications in which 

 naturalists are interested, which experimental evolutionists can 

 bring about, are associated with the formation of specific toxins 

 which might diffuse through the whole system. 



Spencer's Statement of the a priori Argument. — As Herbert 

 Spencer was perhaps the keenest and most convinced upholder 

 of the affirmative position, it seems just to give his statement of 

 the a priori argument. We have made a comment on each of the 

 steps. 



(i) "That changes of structure caused by changes of action 

 must be transmitted, however obscurely, appears to be 

 a deduction from first principles — or if not a specific deduc- 

 tion, still, a general implication." 



" For if an organism, A, has, by any peculiar habit or 



