[81] _Vide_ Karl Semper's "The Natural Conditions of Existence as they affect Animal Life;" Wallace's "Tropical Nature;" Weismann's "Studies in the Theory of Descent;" Darwin's "Animals and Plants under Domestication."
[82] "Principles of Biology," p. 57.
[83] Ps. cxlii. 4, 5.
[84] The "Unseen Universe," 6th Ed., p. 100.