V.
Valenciennes on fresh-water fish, [384].
Variability of mongrels and hybrids, [274].
Variation under domestication, [7].
—— caused by reproductive system being affected by conditions of life, [8].
—— under nature, [44].
——, laws of, [131].
Variations appear at corresponding ages, [14], [86].
——, analogous in distinct species, [159].
Varieties, natural, [44].