XVI ARE ACQUIRED CHARACTERS INHERITED ? 333 



combinations do occur in all these classes in every fresh 

 generation; and breeders know that from, say a hundred 

 half-wild horses, whether from the prairies, the pampas, 

 or the Australian bush, careful selection could obtain — 

 probably in less than a century — very excellent representa- 

 tives of each of the three above-mentioned types of horses. 



Recurring now to the case of the giraffe, whose whole 

 organisation has been modified so as to obtain an almost 

 unlimited feeding-ground from bushes and trees far above 

 the limits eaten off by the tallest antelopes and buffaloes, 

 we see that numerous successive modifications have all 

 worked in this one direction — the large size, the enormous 

 shoulders giving a sloping back, the correspondingly long 

 neck, the long head, and the elongated prehensile tongue, 

 so that a full-grown male giraffe can feed up to twenty 

 feet above the ground. 



In considering how this was brought about we must 

 remember that the struggle for existence is very inter- 

 mittent in character. A severe drought causing a 

 scarcity of herbage, and leading the antelopes and 

 buffaloes to compete with the giraffes for the foliage near 

 the ground, may occur at intervals of from twenty years 

 to a century. When such droughts occur, animals that 

 can feed half a foot higher than others would survive ; not 

 one individual here and there, but the tenth or twentieth 

 part of the whole population in a given district, amounting, 

 perhaps, to many thousands of individuals. These taller 

 survivors would go on increasing for another long period, 

 in the meantime being subject to the usual struggle with 

 wild beasts and other dangers, natural selection keeping 

 the whole organism up to the mark, till another period of 

 scarcity led again to an elimination of the shortest. 

 Those that survived would not be all alike ; some would 

 gain the increased feeding power by higher shoulders, 

 some by longer neck, or longer head, or more extensible 

 tongue, or by various combinations of these variations ; 

 and the regular elimination of the weaker or less active 

 in every year of the intervening periods, together with the 

 equalising result of constant intercrossing, would produce 

 a race possessing the one essential character of lofty 



