374 The Outline of Science 



they are directly induced in the individual lifetime by peculiarities, 

 in habits and surroundings, including food. They are also called 

 "acquired characters" a very unfortunate term. They are 

 impressed from without, whereas true variations and mutations 

 are expressed from within. 



Modifications are indents or imprints, variations are out- 

 comes. According to the evolution theory of Lamarck, which 

 Darwin accepted in some measure, the characters of a race may 

 slowly change through the cumulative inheritance of the modifica- 

 tions which individuals acquire as the result of peculiarities in 

 use and disuse, and in surroundings. A cave animal is blind, 

 according to Lamarck, as the result of ages of living in dark- 

 ness, during which the eyes have suffered from disuse. The 

 modern Darwinian would point to the fact that constitutional 

 or germinal variations in eyes are common. Variants with weak 

 eyes and with a bias in that direction would naturally seek out 

 caves. The giraffe has got a very long straight neck because of 

 the cumulative result of generation after generation of stretching 

 up to the branches of the acacia-trees. With certain provisos 

 Darwin inclined to accept this view as supplementary to his own. 

 But the modern Darwinian would point to the fact that con- 

 stitutional or germinal variations in the proportions of different 

 parts of the body are common. Giraffe variants in the direction 

 of a long neck would prosper, and would become the leaders of 

 the race. Long noses often run in families, but the length of 

 the nose is not due to the vigour with which generations have 

 used the handkerchief. 



No one doubts the reality of modifications: one has only to 

 look at the tanned skin of the African explorer. But what is 

 doubtful is that a modification can be passed on from the individ- 

 ual that acquires it to his offspring passed on as such or in 

 any representative degree. The modification may be very 

 important, even life-saving, for the individual, but unless it can 

 be transmitted it is not in any direct way important for the race. 



