58 PHILOSOPHICAL NOTES ON 



to surroundings ; but I would say that it is as difficult to disprove 

 that what is called a congenital modification has been brought 

 about originally by any other factor than that of its surroundings. 



Some might say that, if the struggle for existence and survival 

 of the Jittest is enough to explain all the adaptations we see, where 

 is the advantage of supposing that the surroundings too act as 

 modifiers of living things ? 



It is forgotten that struggle for existence is a part of the 

 surroundings, and that the whole of the universe is pervaded by 

 electrical influence, which, in turn, influences the polarity of 

 atoms, and, therefore, must act as a modifier of living things, 

 whether this influence act directly on the reproductive cells, or 

 indirectly on them through their surrounding somatic cells. 



No one who has seen the characteristic forms of plants in 

 digenous to rocky, arid countries, to deserts, to mountain surfaces, 

 to tropical damp climates, can have any doubt whatever that 

 climate and soil have been two great factors in modifying plants. 

 What but the dryness of climate and soil could have so de- 

 pauperized branches and leaves as to gradually reduce them to 

 thorns and spines ? There is no more proof that congenital 

 variations, uninfluenced by climate and soil, became eventually 

 fitted to the surroundings, than there is proof that climate and 

 soil acting on a plastic, sensitive, body caused congenital modi- 

 fications to develop. But I do not see how we can throw aside 

 surroundings, and lean entirely on congenital variations produced 

 solely by the union of male and female cells. In the case of 

 animals, for instance, we would be throwing aside the whole of 

 the nervous influence, which is of the most searching and 

 penetrating kind !* 



All modifying factors, whatever these may be, would have 

 caused variation to " run mad," were it not for the restraining 

 force of heredity, by which the preservation of useful qualities has 

 been effected. 



No one can walk through the streets of London and come face 

 to face with the thousands of persons he may meet, and not be 

 struck with the astonishing fact that although no two are alike, 

 there is a characteristic type underlying the whole of them. 

 Variation is limited by this force of heredity. Just imagine, then, 

 how many millions of years were needed to bring about the 



* I have discussed this question further under Variation, 



