Organic Evolution. 235 



Once more, let it be clearly remembered that a large 

 and important school of zoologists reject altogether use or 

 disuse as a factor in variation. They believe that those 

 germs are selected through natural selection in which 

 there is an increased tendency to use or disuse of certain 

 organs. In this, however, we are all agreed. The real 

 question is what is the source of origin of this tendency. 

 On the view of germinal origin, we are forced back on 

 unknown physical or chemical influences in no wise related 

 in origin (though, of course, related in result) with the use 

 or disuse to which they give rise. 



So far the main distinction between the two biological 

 schools seems to be that the one, placing the origin of 

 variation in the body-tissues, regards the variations as 

 evoked in direct reaction to physical or chemical influences ; 

 while the other, placing the origin of variation in the 

 germ, regards the variations as of fortuitous origin. 



I do not use the phrase, " of fortuitous origin," as in 

 any sense discrediting the theory. I am not attempting 

 the cheap artifice of damning a view that does not happen 

 to be my own with a phrase or a nickname. And I there- 

 fore hasten to point out what variations I do believe to 

 have had a fortuitous origin. The phrase is often mis- 

 understood, and they will serve to explain its meaning. 



If the reader will kindly refer to the tables of variations 

 in the bats' wings (Figs. 14-17), he will see that there are 

 a great number of bones which vary in length and vary 

 independently. And if he will also refer to Fig. 18, in 

 which seven species of bats are compared, he will see that 

 the differences arise from the increased length of one set 

 of bones in one species and another set of bones in another 

 species. Now, let us suppose that the long, swallow-like 

 wing of the noctule, a high flyer with rapid wing-strokes, 

 that catches insects in full flight, and the broad wings of 

 the horse-shoe, a low flyer, flapping slowly, and, at any 

 rate, sometimes catching insects on the ground, and cover- 

 ing'them with its wings as with a net ; let us suppose, I 

 say, that to each species its special form of wing is an 



