i66 THE POPULAR SCIENCE MONTHLY. 



traces of the father were cases in which the mother was of pure 

 breed. Speaking of the results of these crossings in the second 

 generation "having 75 per cent of English blood," M. Nouel 

 says : " The lambs thrive, wear a beautiful appearance, and com- 

 plete the joy of the breeder. . . . No sooner are the lambs weaned 

 than their strength, their vigor, and their beauty begin to decay. 

 ... At last the constitution gives way. ... he remains stunted 

 for life," the constitution being thus proved unstable or un- 

 adapted to the requirements. How, then, did M. Nouel succeed 

 in obtaining a desirable combination of a fine English breed with 

 the relatively poor French breeds ? 



"He took an animal from 'flocks originally sprung from a mixture of the two 

 distinct races that are established in these two provinces [Berry and La Sologne],' 

 and these he 'united with animals of another mixed breed. . . . which blended 

 the Tourangelle and native Merino blood of La Beauce and Touraine, and ob- 

 tained a mixture of all four races ' without decided character, without fixity. . . . 

 but possessing the advantage of being used to our climate and management.' 



"Putting one of these 'mixed-blood ewes to a pure New-Kent ram. . . . one 

 obtains a lamb containing fifty-hundredths of the purest and most ancient Eng- 

 lish blood, with twelve and a half hundredths of four different French races, 

 which are individually lost in the preponderance of English blood, and disappear 

 almost entirely, leaving the improving type in the ascendant. ... All the lambs 

 produced strikingly resembled each other, and even Englishmen took them for 

 animals of their own country.' " 



M. Nouel goes on to remark that when this derived breed was 

 bred with itself, the marks of the French breeds were lost. " Some 

 slight traces could be detected by experts, but these soon disap- 

 peared." 



Thus, we get proof that relatively pure constitutions predomi- 

 nate in progeny over much mixed constitutions. The reason is 

 not difficult to see. Every organism tends to become adapted to 

 its conditions of life ; and all the structures of a species, accus- 

 tomed through multitudinous generations to the climate, food, 

 and various influences of its locality, are molded into harmoni- 

 ous co-operation favorable to life in that locality: the result 

 being that in the development of each young individual, the 

 tendencies conspire to produce the fit organization. It is other- 

 wise when the species is removed to a habitat of different charac- 

 ter, or when it is of mixed breed. In the one case its organs, 

 partially out of harmony with the requirements of its new life, 

 become partially out of harmony with one another ; since, while 

 one influence, say of climate, is but little changed, another influ- 

 ence, say of food, is much changed ; and consequently, the per- 

 turbed relations of the organs interfere with their original stable 

 equilibrium. Still more in the other case is there a disturbance 

 of equilibrium. In a mongrel the constitution derived from each 



