Chap. XXVni. CONCLUDING KEMAEKS. 423 



oats, peas, beans, lentils, poppies, — cultivated for their seed 

 by the ancient Lake-inhabitants of Switzerland, were all 

 smaller than the seeds of our existing varieties. Riitimeyer 

 has shown that the sheep and cattle which, were kept by ttie 

 earlier Lake-inhabitants were likewise smaller than our 

 present breeds. In the middens of Denmark, the earliest dog 

 of whicb the remains have been found was the weakest ; this 

 w^as succeeded during the Bronze age by a stronger kind, and 

 this again during the Iron age by one still stronger. The 

 sheep of Denmark during the Bronze period had extra- 

 ordinarily slender limbs, and the horse was smaller than our 

 present animal.^ No doubt in most of these cases the new 

 and larger breeds were introduced from foreign lands by the 

 immigration of new hordes of men. But it is not probable that 

 each larger breed, which in the course of time has supplanted 

 a previous and smaller breed, was the descendant of a distinct 

 and larger species ; it is far more probable that the domestic 

 races of our various animals were gradually improved in 

 different parts of the great Europajo- Asiatic continent, and 

 thence spread to other countries. This fact of the gradual 

 increase in size of our domestic animals is all the more 

 striking as certain wild or half-wild animals, such as red- 

 deer, aurochs, park-cattle, and boars,^" have within nearly the 

 same period decreased in size. 



The conditions favourable to selection by man are, — the 

 closest attention to every character, — long-continued per- 

 severance, — facility in matching or separating animals, — and 

 especially a large number being kept, so that the inferior 

 individuals may be freely rejected or destroyed, and the better 

 ones preserved. AVhen many are kept there will also be a 

 greater chance of the occurrence of well-marked deviations of 

 tstructure. Length of time is all-important ; for as each cha- 

 racter, in order to become strongly pronounced, has to be 

 augumented by the selection of successive variations of the 

 same kind, this can be effected only during a long series of 

 generations. Length of time will, also, allow any new 

 feature to become fixed by the continued rejection of those 



^ Morlot, * Soc. Vaud. des Scien. ^" Riitimeyer, ' Die Fauna der 



Nat.' Mars, 1860, p. 298. Pfahlbauten/ 1861, s. 30. 



