4*2 BIOLOGICAL SOCIETY OF WASHINGTON. 



the improvement of the special opportunities offered by the en 

 vironment. We have also seen that these opportunities have 

 presented themselves at long and irregular intervals, and, as it 

 were, by chance. In this sense there is only a difference of 

 degree between these normal and legitimate influences and 

 those which I have called extra normal or illegitimate. Their 

 occurrence was fortuitous. They were the result of accidental 

 variations in an advantageous direction seized upon by nature 

 for the creation of higher types of life. 



There is a school of evolutionists who maintain that this is 

 the only way in which 'progress takes place. This is held to 

 be the strictly Darwinian view, as opposed to the Lamarckian 

 view that the "appetencies," as Lamarck called them, i. e.< 

 the individual efforts, strivings, and struggles of the organism 

 in advantageous directions, aid in determining what the new 

 and improved type shall be. In a paper which I had the 

 honor to read before this society over a year ago on ''Fortui 

 tous Variation as illustrated by the genus Eupatorium " * I 

 endeavored to show that this fortuitous variation was often 

 successful even when no apparent advantage could result there 

 from. The tendency to vary is in all directions, as from the 

 center toward the surface of a sphere, and variation will take 

 place in every direction which does not prove so disadvantage 

 ous as to render life impossible. In by far the greater number 

 of cases the advantage or disadvantage is slight or imperceptible, 

 and changes go on without improvement or deterioration, 

 causing a great number of equally vigorous forms to arise, all 

 differing more or less from one another. This accounts chiefly 

 for the varied and manifold in nature, and but for this law, 

 hitherto, so far as I am aware, unobserved, nature would be 



* See abstract (all that was published) in Nature (London) for July 

 25, 1889 (Vol. XL, p. 310). 



