HEREDITARY TRANSMISSION AND VARIATION. 101 



the nature of flight, and the powers of flight, — so-call- 

 ed " homing " birds having enormous flying powers ;* 

 while, on the other hand, the little Tumbler is so called 

 because of its extraordinary faculty of turning head 

 over heels in the air, instead of pursuing a distinct 

 course. And, lastly, the dispositions and voices of the 

 birds may vary. Thus the case of the pigeons shows 

 you that there is hardly a single particular, — whether 

 of instinct, or habit, or bony structure, or of plumage, 

 — of either the internal economy or the external shape, 

 in which some variation or change may not take place, 

 which, by selective breeding, may become perpetuated, 

 and form the foundation of, and give rise to, a new 

 race. 



If you carry in your mind's eye these four varieties 

 of pigeons, you will bear with you as good a notion as 

 you can have, perhaps, of the enormous extent to which 

 a deviation from a primitive type may be carried by 

 means of this process of selective breeding. 



* The " Carrier" I learn from Mr. Tegetmeier, does not carry ; 

 a higli-bred bird of this breed being but a poor flier. The birds 

 which fly long distances, and come home, — " homing " birds, — 

 and are consequently used as carriers, are not " carriers " in the 

 fancy sense. 



