16 
skull of the latter variety. This fact at once illustrates the 
power which careful and scientific agriculturists . have . in 
changing the character of particular breeds — a practice which 
they are pursuing constantly. “The improved Essex pigs, 
for example, chiefly owe their present excellent qualities, 
says Mr. Darwin, “ to crosses originally made by Lord 
Western with the Neapolitan race, and to subsequent crosses 
with the Berkshire breed.”* * * § So with our British sheep. The 
Oxfordshire downs, which now rank as an established breed, 
were produced about the year 1830, by crossing Hampshire 
or Southdown ewes with Ootswold rams. So with our fowls. 
The Sebright bantam fowl was formed about sixty years ago, 
by a complicated cross, which I need not here describe. f 
29. It should be remarked, however, that for the production 
of new breeds through complex crosses, the most careful and 
unremitting selection of well- chosen pairs through continuous 
generations is required. This remark is especially important 
as bearing upon the human problem now under discussion \ 
for that simple and temporary modifications of form, may be 
produced by occasional crossings, whether among animals oi 
men, no one who knows anything about the subject will, en- 
tertain a doubt. But to produce permanent uniformity in a 
crossed breed, careful selection and rigorous weeding are in 
the highest degree necessary, without which any particular 
variation desired will be always intermittent and uncertain. 
30. Sometimes an abnormal specimen, which the owner 
desires to perpetuate, unexpectedly and spontaneously makes 
its appearance. In this case, the necessity for crossing it 
with other breeds is not so important as its careful pro- 
pagation through the occasionally transmitted specimens of 
its own type ; under which circumstances a new and more 
strongly-marked variety may be established than could pos- 
sibly have been produced, even with the greatest skill, under 
other circumstances. Thus, in one recorded case, when a 
rabbit produced among her litter a young one having a single 
ear, the owner afterwards established a breed which steadily 
produced one-eared rabbits. J Again, in Massachusetts 
(United States), a ram having been accidentally born with 
short crooked legs and a long back, it was (for reasons which 
need not here be explained) soon multiplied and raised into a 
new stock, known by the name of the Ancon breed. § 
* See Darwin, Variatioyis of Animals and Plants , vol. i. p. 78. 
t See Darwin, idem, vol. ii. pp. 95, 96. 
X Anderson’s Recreations in Agriculture, &c.,- vol. i. 68. . 
§ This Ancon breed has since been allowed to die out, having been 
supplanted by the Merino breed. 
