200 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
ordinary workers (sterile females of the first type), soldiers (sterile 
females of the second type), and sometimes officers (especially large 
and powerful sterile females that seem to direct the line ‘of march in 
legionary ants). All of these casts are produced from the eggs of one 
female and are the result of various special diets permitted the larvae 
by the workers. Among bees, similarly, there is one queen, a number 
of drones (males), and the sterile female workers, who perform the 
functions of nursing the larvae, cleaning up the hive, collecting pollen 
and nectar, and making honey and wax. Detailed accounts of the 
lives of bees have been given by various authors, notably by Maeter- 
linck in his Life of the Bee. 
COLOR IN ANIMALS 
“The phenomena of color in both animals and plants,” says 
Metcalf,! ‘“‘are among the most remarkable and interesting in the 
whole realm of nature. It is not so much the way in which the color 
is produced, whether by pigments or by refraction, that interests us 
in this connection, as it is the uses to which colors are put. Let us 
first refer to the colors of animals. 
“According to the uses to which colors in animals are put, we 
may classify them, for purposes of description, as follows: 
“Indifferent coloration, not useful, so far as we can judge; 
Colors of direct physiological value; 
Protective coloration and resemblances; 
Aggressive coloration and resemblances; 
Alluring coloration and resemblances; 
Warning coloration; 
Immunity coloration; 
Mimetic coloration and resemblances; 
A. Protective 
B. Aggressive 
Signals and recognition marks; 
Confusing coloration; 
Sexual coloration.” 
A few examples of these categories of animal coloration will serve 
to illustrate the ways in which they are believed to be adaptive and 
thus better to fit the organism for its struggle for existence. 
Protective resemblance.— Many animals that live at or near the 
surface of the sea are practically transparent. Fishes are commonly 
=M, M. Metcalf, Organic Evolution (1911), 
