Note DY — Chapter VI · ORGANIC EVOLUTION. (continued 2)

Similarly, from a chance sport of a one-eared rabbit, Anderson formed a breed which steadily produced one-eared rabbits ("Animals and Plants under Domestication," vol. i. p. 456). This is an example of asymmetrical variation. Variations are generally, but not always, symmetrical. Superficial colour-variations are sometimes asymmetrical. Gasteropod molluscs are nearly always asymmetrically developed. Among insects, Anisognathus affords an example of the asymmetrical development of the mandible. Our right-handedness is a mark of asymmetry.