318 



LAWS OF VARIATION. 



Chap. XXIV. 



and are furnished with claws. In the common Hen, the spurs and comb 

 are rudimentary, but in certain breeds these become, independently of 

 age or disease of the ovaria, well developed. The stallion has canine teeth, 

 but the mare has only traces of the alveoli, which, as I am informed by 



iminent veterinarv Mr 



These nodules, however, sometimes become deve- 



and coated 



imperfect teeth, protruding through the gums 



gular nodul 

 loped into 



with enamel ; and occasionally they grow to a third or even a fourth of 

 the length of the canines in the stallion. With plants I do not know 

 whether the redevelopment of rudimentary organs occurs more frequently 

 under culture than under nature. Perhaps the pear-tree may be a case in 

 point, for when wild it bears thorns, which though useful as a protection 

 are formed of branches in a rudimentary condition, but, when the tree is 

 cultivated, the thorns are reconverted into branches. 



Finally, though org 



which must be classed as rudi 



nientary frequently occur in our domesticated animals and 

 cultivated plants, these have generally been formed suddenly, 

 through an arrest of development. They usually differ in 

 appearance from the rudiments which so frequently characterise 

 natural species. In the latter, rudimentary organs have been 

 slowly formed through continued disuse, acting by inheritance 

 at a corresponding age, aided by the principle of the economy 



of growth, all under the con 

 domesticated animals, on the 



ol of natural selection 



With 



l the other hand, the principle of eco- 



nomy is far from coming into action, and their organs, although 

 often slightly reduced by disuse, are not thus almost obliterated 

 with mere rudiments left. 



v 



I 



I 



