The return to England was the date of onset for a record of continuous illness, aggravated by his marriage, apparently, for his misery increased progressively after it. So much so that he was forced to leave London altogether so as to avoid the strain of social life, even that of meeting his scientific friends or attending scientific society meetings fatiguing him to exhaustion. After such occasions there would be attacks of violent shivering, with vomiting and giddiness. It was necessary for him to impose upon himself an absolute régime of daily routine. Any interference with it upset him completely, and made it impossible for him to do any work. Early morning was the only time for physical as we; as mental exertion. Evening found him thoroughly used up, with every move an effort. Insomnia made him its prey. A curious sensitiveness to heat and cold distressed him. In 1859, when the "Origin of Species" appeared, he wrote to a friend that his health had quite failed, and that indigestion, headaches, with a looming hopeless breakdown of body and mind made his life a burden and a curse. The twenty years of research he devoted to the problems of evolution were one long torture. For sixteen more years, during which he worked upon and produced immortal classics of biology, he was the most wretched and unhappy sufferer from neurasthenia. His life was a continuous alternation of small doses of work and large doses of rest. So he was enabled to publish twenty-three volumes of original writing and fifty-one scientific papers. Living a sort of quasi-sanitarium life, with the rules and regulations of one undergoing a rest cure for thirty-six years, he thus accomplished infinitely more than the millions who have led the strenuous life. That he thus survived, as a genius, among the perils of an intellectual nature in an environment for which his adrenals sentenced him to destruction, must be put down in large measure to the ministrations and good sense of wife and children who supplied him with the endocrine energy he lacked. All these details I have given in the attempt to analyze the internal secretion constitution of this great man of genius, to establish that he really suffered from inadequate function of his adrenal glands, for the symptoms of chronic though benign adrenal insufficiency coincide in their mass effect with the story of his life. He was not a good animal, as Herbert Spencer declared was a first sine qua non of the successful life. He was a poor animal, the poorest of animals, because he possessed poor adrenals. What saved him was his congenitally superior pituitary (the nidus of genius) and the overacting thyroid, which combined to compensate to some extent for his fundamental lack. According to his son he rose early because he could not lie in bed, and he would have liked to get up earlier than he did.