American Breeders Magazine 2(4): 313 (4th quarter, 1911)

Chas. E. Woodruff, Surgeon U. S. Army, Panay, P. I.

My observations on the effects of light and heat on the organism of animals have elicited some extremely important facts as to the survival value of colors. My former ignorance of the reasons why the Arab horse in a hot climate with his black skin tends to have white hair, and the Chinese pony in a cold climate the same, cost me exactly $200 ten years ago, and if the Government will act on the hint it will save $200,000 in a very short time. Breeders must breed for color where color enhances work, power, and endurance. * * * *

Since then, I have obtained other facts which lead me to believe the matter of color in animals much more important than I formerly thought. The white horse or mule is particularly fitted for climates where the day is hot and the night cool, for by reflecting sun rays it remains comfortable when the black dies of thermic fever; and at night it does not radiate to colder surroundings, remaining comfortable when the black gets pneumonia even though blanketed.

American Breeders Magazine 3(4): 156-157 (4th quarter, 1912)

The Best Color for Horses in the Tropics. Lieut. Col. Charles E. Woodruff, Med. Corps, U. S. Army, Journal of the U. S. Cavalry Association, September 1911. Pp. 243-263.

Dr. Woodruff has been persistently pursuing the question of the influence of light on living matter and since the publication of his Expansion of Races, and The Effects of Tropical Light on White Man has in various writings added facts of material values until he has succeeded in bringing together an amount of data which command attention, particularly because of their practical value. The article under consideration is written mainly with the view of eliciting further information on the matter of skin and hair color of horses, mules and cattle for tropical countries and incidentally of all stock much exposed to sunlight.

Dr. Woodruff maintains that "a few belated physicians still profess to believe that nature made a mistake in pigmenting living forms in light countries, but that is no reason why men should be so foolish as to try to acclimatize where God cannot do it." "Acclimatization is now used only by ignoramuses."

He believes that in transferring stock of whatever kind, from one climate and latitude to another, skin and hair coloring is an item that must be considered. If not, the lethal effect of light will effect a selection by killing of the least fit and this is true in tropical countries, climates with intense sunlight, or even large cities where during "hot waves" conditions exist, resembling those in tropical climates.

Best adopted in the tropics are animals with white, gray or sorrel, or mud colored hair and black skin, while for animals in the north temperate zones the best are black skins with either white or light coats.