THE CROSSING, AC, OF CATTLE, ET AL. 325 



This Bos, from which, also, all our domestic Cattle 

 have descended, is described by Csesar, as being not 

 much inferior to the elephant in size. 



The decrease in size, from interbreeding, is due to 

 the reverse reason of that of the increase in size, 

 attendant upon crossing. The latter namely, increase 

 of size resulting from crossing two breeds, is owing to 

 room having to be made, in the offspring, to allow of 

 the combination of the characters contributed by both 

 parents. The decrease in size referred to, is due to 

 the saving of interstitial space, due to the augmenta- 

 tion of the similar defects of the parents interbred. 



The principle of the decrease in size, from interbreed- 

 ing animals, with but slight defects of proportion, is 

 further illustrated by the case of the Sebright Bantam 

 (Fowl). This animal was produced by many very 

 complicated crosses, until, at least, the bases of all or 

 nearly all the characters of the Fowl, were united in it. 

 Then it was closely interbred for a long period, which 

 gradually reduced its size, so that it now weighs but 

 one pound! 



It is clear, that, when the different breeds cross, 

 some of the deficiencies of each, are corrected by the 

 positive differences, or by the special excellence, of 

 another; and that such result must, ex hypotkesi,brmg, 

 with it, increased fertility and constitutional vigor. 

 This is shown by Darwin's facts. But, the increase in 

 fertility is less, in the case of Cattle, and of Sheep ; be- 

 cause they are little divergent in character, and because 

 there is little room for improvement. The crossing of 



varieties of the Pigeon, and of varieties of the Fowl, is 

 28* 



