Theory of Circulation by Respiration

voted to the revision and enlargement of my historical works; but early is 1846, having determined on making the tour of the United States, I resolved first to prepare my theory for the press. In the introduction, I remarked, "The house of clay in which the mind dwells must receive a portion of its care; and that which I have bestowed on mine has proceeded on a belief in the truth of the theory herein advocated, as undoubting as that in the laws of gravitation; and when any new fact, or any remark of an author, relating to my theory came under my observation, I noted it down and laid it by with its kindred. About to set out on a long journey, and aware that my field of vision had thus enlarged, I felt it my duty to put together the principal of my remarks, that I might so leave the subject, that, in case anything should prevent my return, it would be in a form equal to the present slate in which the theory exists in my own mind."

The time I had spent in devotion to this theory, the many rebuffs I had m