270 L4Y SERMONS, ADDRESSES, AND REVIEWS. [xll 



parts, strength or weakness of constitution, tendency to 

 fatten or to remain lean, to give much or little milk, 

 speed, strength, temper, intelligence, special instincts; 

 there is not one of these characters whose transmission 

 is not an e very-day occurrence within the experience 

 of cattle-breeders, stock-farmers, horse-dealers, and 

 dog and poultry fanciers. Nay, it is only the other 

 day that an eminent physiologist, Dr. Brown-Secjuard, 

 communicated to the Eoyal Society his discovery 

 that epilepsy, artificially produced in guinea-pigs, by a 

 means which he has discovered, is transmitted to their 

 offspring. 



But a race, once produced, is no more a fixed and 

 immutable entity than the stock whence it sprang ; 

 variations arise among its members, and as these varia- 

 tions are transmitted like any others, new races may be 

 developed out of the pre-existing one ad infinitum, or, 

 at least, within any limit at present determined. Given 

 sufficient time and sufficiently careful selection, and the 

 multitude of races which may arise from a common 

 stock is as astonishing as are the extreme structural 

 differences which they may present. A remarkable 

 example of this is to be found in the rock-pigeon, which 

 Mr. Darwin has, in our opinion, satisfactorily demon- 

 strated to be the progenitor of all our domestic pigeons, 

 of which there are certainly more than a hundred well- 

 marked races. The most noteworthy of these races are, 

 the four great stocks known to the " fancy " as tumblers, 

 pouters, carriers, and fantails ; birds which not only differ 

 most singularly in size, colour, and habits, but in the 

 form of the beak and of the skull : in the proportions of 

 the beak to the skull ; in the number of tail-feathers ; in 

 the absolute and relative size of the feet ; in the presence 

 or absence of the uropygial gland ; in the number of 

 vertebras in the back; in short, in precisely those cha- 



