Accidental Variation. 155 



any given result in animal life, such as is seen in 

 the complex societies of social insects, can be accom- 

 plished by these agencies working even for untold 

 ages, does not follow. Some results may follow, 

 but they must be such as these agencies have some 

 competency to produce ; and we must have some 

 reasonable account of the origin of certain elements 

 of the animal economy, as well as of their modifi- 

 cation. But it is asked at once, If you grant "acci- 

 dental variation" *and indefinite periods of time for 

 the work of selection, have you not the elements 

 of working out any supposable result ? We answer, 

 No. We can understand that a painter by throw- 

 ing his sponge, in anger or desperation, upon his 

 picture, might accidentally paint the foam upon the 

 mouth of the dog with a naturalness that his pencil 

 had failed to give. We can believe that this has 

 been done. But now if we were told that a picture, 

 like one of Landseer's or Rosa Bonheur's, could be 

 made by throwing paint sponges against a canvas 

 an indefinite number of times, we should not be- 

 lieve it ; even if the experiment could be tried every 

 day for millions of years. And although we can 



* We use the words " accidental variation," to signify any 

 change that may occur in an organic being under new condi- 

 tions — any change not specially provided for in his plan of de- 

 velopment — any change by which individuals depart from the 

 normal type of the species. It is in this way that we under- 

 stood Mr. Darwin to use the words, and in the same way, we 

 understand Mr, Wright to use them, in his defence of Darwin, 

 written since these Lectures were delivered. (North Am, Rev., 

 July 1871.) No one who understands Mr. Darwin, would accuse 

 him of using the word " accidental " in any such sense as to 

 imply any denial of causality. 



