as well as to record the fact. "One of the noblest lessons left to the world" by Darwin is this, Mr. Frank Cramer tells us,--"this, which to him amounted to a profound, almost religious, conviction, that every fact in nature, no matter how insignificant, every stripe of color, every tint of flowers, the length of an orchid's nectary, unusual height in a plant, all the infinite variety of apparently insignificant things, is full of significance. For him it was an historical record, the revelation of a cause, the lurking-place of a principle."
According to the theory of evolution every structure of to-day finds its meaning in some condition of the past. The inside of an animal tells what it really is, for it bears the record of heredity. The outside of an animal tells where its ancestors have been, for it bears record of concessions to environment. Similarity in essential structure is known as homology. By the theory of evolution homology, wherever it is found, is proof of blood-relationship.