Chap. XIII. 



EEVEKSION. 



29 



the son more closely resembles his maternal than his paternal 

 grandsire in some male attribute, as in any peculiarity in the 

 beard of man, the horns of the bull, the hackles or comb of 

 the cock, or, as in certain diseases necessarily confined to the 

 male sex ; for the mother cannot possess or exhibit such male 

 attributes, yet the child has inherited them, through her blood, 

 from his maternal grandsire. 



The cases of reversion may be divided into two main classes, 

 which, however, in some instances, blend into each other ; 

 namely, first, those occurring in a variety or race which has 

 not been crossed, but has lost by variation some character 

 that it formerly possessed, and which afterwards reappears. 

 The second class includes all cases in which a distinguishable 

 individual, sub-variety, race, or species, has at some former 

 period been crossed with a distinct form, and a character derived 

 from this cross, after having disappeared during one or several 

 generations, suddenly reappears. A third class, differing only 

 in the manner of reproduction, might be formed to include 

 all cases of reversion effected by means of buds, and therefore 

 independent of true or seminal generation. Perhaps even a 

 fourth class might be instituted, to include reversions by seg- 

 ments in the same individual flower or fruit, and in different 

 parts of the body in the same individual animal as it grows old. 

 But the two first main classes will be sufficient for our purpose. 



Reversion to lost Characters by pure or uncrossed forms. 



Striking instances of this first class of cases were given in the 

 sixth chapter, namely, of the occasional reappearance, in variously- 

 coloured pure breeds of the pigeon, of blue birds with all the 

 marks which characterise the wild Columbia livia. Similar cases 

 were given in the case of the fowl. With the common ass, as we 

 now know that the legs of the wild progenitor are striped, we 

 may feel assured that the occasional appearance of such stripes 

 in the domestic animal is a case of simple reversion. But I 

 shall be compelled to refer again to these cases, and therefore 

 will here pass them over. 



The aboriginal species from which our domesticated cattle and 

 sheep are descended, no doubt possessed horns ; but several horn- 

 less breeds are now well established. Yet in these— for instance, 



