200 Variations and Orthoplasy 



tions ; for we only have to say that there is some acquired 

 physiological accommodation with which the harshness of 

 the wool is associated or correlated ; this physiological 

 accommodation utilizes variations present in a greater or 

 less number of sheep ; these sheep survive by natural 

 selection, and produce the next generation ; the next and 

 subsequent generations have further variations in the direc- 

 tion of this physiological adaptation ; and with it will go 

 the increased tendency to have harshness of wool. The 

 rapidity with which this process would go on would depend 

 upon the importance and the difficulty of the physiological 

 adjustment. Say, for example, that the change in diet, 

 soil, climate, etc., lays the imported sheep open to a certain 

 disease ; therefore, a certain strength, ruggedness, vigour 

 of constitution, which carries with it harshness of wool, is 

 necessary to give recovery and gradual immunity from this 

 disease ; then the sheep which lived would continue the 

 variations which tended to permanent immunity, and with 

 them would go the harshness of wool. That this is the case 

 seems tolerably plain from the nature of the character, and 

 from the fact that it increases from one shearing to another. 

 Such a change in the quality of wool could not take place 

 incidentally ; it could not arise by selection without some 

 specific utility ; it must represent some deep-seated adjust- 

 ment. The quickness with which it takes effect in the 

 individual sheep would show the likelihood that its rapid 

 individual acquisition was necessary to save the sheep. Put 

 tersely, the sheep are saved by accommodation, and with 

 them are saved both variations toward that accommodation 

 and also other characters which are correlated with these.^ 



1 It is necessary to note that the question whether these sheep retain the 

 harshness of wool when taken back to Ohio is not answered by our informers. 



