Quatrefages, in Revue d. deux Mondes, Dec. 1860:814—“If one places himself exclusively upon the plane of the natural sciences, it is impossible not to conclude in favor of the monogenist doctrine.” Wagner, quoted in Bib. Sac., 19:607—“Species—the collective total of individuals which are capable of producing one with another an uninterruptedly fertile progeny.” Pickering, Races of Man, 316—“There is no middle ground between the admission of eleven distinct species in the human family and their reduction to one. The latter opinion implies a central point of origin.” There is an impossibility of deciding how many races there are, if we once allow that there are more than one. While Pickering would say eleven, Agassiz says eight, Morton twenty-two, and Burke sixty-five. Modern science all tends to the derivation of each family from a single germ. Other common characteristics of all races of men, in addition to those mentioned in the text, are the duration of pregnancy, the normal temperature of the body, the mean frequency of the pulse, the liability to the same diseases. Meehan, State Botanist of Pennsylvania, maintains that hybrid vegetable products are no more sterile than are ordinary plants (Independent, Aug. 21, 1884). E. B. Tylor, art.: Anthropology, in Encyc. Britannica: “On the whole it may be asserted that the doctrine of the unity of mankind now stands on a firmer basis than in previous ages.” Darwin, Animals and Plants under Domestication, 1:39—“From the resemblance in several countries of the half-domesticated dogs to the wild species still living there, from the facility with which they can be crossed together, from even half tamed animals being so much valued by savages, and from the other circumstances previously remarked on which favor domestication, it is highly probable that the domestic dogs of the world have descended from two good species of wolf (_viz._, _Canis lupus_ and _Canis latrans_), and from two or three other doubtful species of wolves (namely, the European, Indian and North American forms); from at least one or two South American canine species; from several races or species of the jackal; and perhaps from one or more extinct species.” Dr. E. M. Moore tried unsuccessfully to produce offspring by pairing a Newfoundland dog and a wolf-like dog from Canada. He only proved anew the repugnance of even slightly separated species toward one another. B. Unity of species is presumptive evidence of unity of origin. Oneness of origin furnishes the simplest explanation of specific uniformity, if indeed the very conception of species does not imply the repetition and reproduction of a primordial type-idea impressed at its creation upon an individual empowered to transmit this type-idea to its successors.