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THE /5 9 Y 
AM ERICAN NATURALIST 
Vor. XXVIIL ^ July, A E 331 
ANIMAL MECHANICS: 
By Dr. Manty MILES. 
Reference was made to a former lecture before the Michigan 
Short-horn Cattle Association, in which the relations of hered- 
ity and variation to the improvement of live stock were dis- 
cussed, and attention was called to the flexibility of the con- 
stitution of domestic animals that made them susceptible to 
the modifying influences of the conditions in which they are 
placed—so that variations are constantly produced by changes 
in food and management, and constant care must be exercised |. 
to select the animals presenting desirable variations to fix and 
retain them as inherited characters. 
In presenting these fundamental principles in the improve- 
ment of animals, many important details were necessarily 
omitted, and at the present time my purpose is to supplement - 
the general subject of heredity and variation, by calling atten- 
tion to some of the latest contributions of science to the 
philosophy of feeding, and notice their relations to the prin- 
ciples of selecting breeding stock, that are often overlooked by 
inexperienced breeders in their efforts to improve their ani- 
mals in special qualities. 
In the lecture referred to, inin were compared to 
machines for converting the vegetable products of the farm 
_ 1Abstract of a lecture before the Michigan Association of Breeders of Improved 
Live sunt. um 17, 1892, 
Mo. Bot. Garden, 
1598. 2 jus 
