the laws of blood-relationship, communicated in a paper to the Royal Society in June, 1872; and the inquiries which are represented in his books on "Hereditary Genius, its Laws and Consequences" (1869); "English Men of Science; their Nature and Nurture" (1874); and "Inquiries into Human Faculty and its Development" (1883).
In the lecture on "Blood-Relationship" he sought to analyze and describe the complicated relation that binds an individual, hereditarily, to his parents and to his brothers, and therefore, by an extension of similar links, to his more distant kinsfolk. By these means he hoped to set forth the doctrines of heredity in a more orderly and explicit manner than was otherwise practicable. "From the well-known circumstance," he said, "that an individual may transmit to his descendants ancestral qualities which he does not himself possess, we are assured that they could not have been altogether destroyed in him, but must have maintained their existence in a latent form. Therefore each individual may properly be conceived as consisting of two parts, one of which is latent and only known to us by its effects on his posterity, while the other is patent and constitutes the person manifest to our senses. The adjacent, and, in a broad sense, separate lines of growth in which the patent and latent elements are situated, diverge from a common group and converge to a common contribution, because they were both evolved out of elements contained in a structureless ovum, and they jointly contribute the elements which form the structureless ova of their offspring. . . . The observed facts of reversion enable us to prove that the latent elements must be greatly more varied than those that are personal or patent." An elaboration of this view, and a more detailed examination of the phenomena caused the author "to be impressed with the fallacy of reckoning inheritance in the usual way, from parents to offspring, using those words in their popular sense of visible personalities. The span of the true hereditary link connects, not the parent with the offspring, but the primary elements of the two, such as they existed in the newly impregnated ova whence they were respectively developed." In conclusion, he recorded as one result of the investigation, a very clear showing that "large variation in individuals from their parents is not incompatible with the strict doctrine of heredity, but is a consequence of it wherever the breed is impure. I am desirous of applying these considerations to the intellectual and moral gifts of the human race, which is more mongrelized than that of any other domesticated animal. It has been thought by some that the fact of children showing marked individual variation in ability from that of their parents is a proof that intellectual and moral gifts are not strictly transmitted by inheritance. My arguments lead to exactly the opposite result. I show that their great individual variation is a necessity under present conditions, and I maintain that results derived from large averages are all that can be required, and all we could expect to obtain, to prove that intellectual and moral
