Chap. XX. METHODICAL SELECTION. 199 



fowls, turkeys, ducks, and geese is notorious; "six-pound 

 ducks are now common, whereas four pounds was formerly the 

 average." As the actual time required to make a change has 

 not often been recorded, it may be worth mentioning that it 

 took Mr. Wicking thirteen years to put a clean white head on 

 an almond tumbler's body, " a triumph," says another fancier, 

 * of which he may be justly proud." 20 



Mr. Toilet, of Betley Hall, selected cows, and especially bulls, 

 descended from good milkers, for the sole purpose of improving 

 his cattle for the production of cheese ; he steadily tested the 

 milk with the lactometer, and in eight years he increased, as I 

 was informed by him, the product in the proportion of four to 

 three. Here is a curious case 21 of steady but slow progress, 

 with the end not as yet fully attained : in 1784 a race of silk- 

 worms was introduced into France, in which one hundred out 

 of the thousand failed to produce white cocoons ; but now, after 

 careful selection during sixty-five generations, the proportion of 

 yellow cocoons has been reduced to thirty-five in the thousand. 



With plants selection has been followed with the same good 

 results as with animals. But the process is simpler, for plants 

 in the great majority of cases bear both sexes. Nevertheless, 

 with most kinds it is necessary to take as much care to pre- 

 vent crosses as with animals or unisexual plants; but with 

 some plants, such as peas, this care does not seem to be neces- 

 sary. With all improved plants, excepting of course those 

 which are propagated by buds, cuttings, &c, it is almost indis- 

 pensable to examine the seedlings and destroy those which 

 depart from the proper type. This is called "roguing," and 

 is, m fact, a form of selection, like the rejection of inferior 

 animals. Experienced horticulturists and agriculturists inces- 

 santly urge every one to preserve the finest plants for the 

 production of seed. 



^ Although plants often present much more conspicuous varia- 

 tions than animals, yet the closest attention is generally requisite 

 to detect each slight and favourable change. Mr. Masters 

 relates 22 how "many a patient hour was devoted," whilst he was 



20 'Poultry Chronicle/ vol. ii., 1855, p. 596. 



1 I* ld - Geoffroy St. Hilaire, ' Hist. Nat. Gen.,' torn. iii. p. 254. 



-- Gardener s Chronicle,' 1850, p. 198. 



