Harvey must now, indeed, have seen his views assured of general reception at no distant date. The same year in which he himself answered Riolan, Dr. James de Back, of Amsterdam, published his work on the Heart,[41] which is written entirely in harmony with the Harveian doctrines, and the celebrated Lazarus Riverius, Professor of Medicine in the University of Montpellier, publicly defended and taught the circulation of the blood.[42] The following year, Paul Marquard Siegel, of Hamburg, produced his commentary on the Motion of the Blood,[43] in which he addresses himself particularly to a refutation of Riolanus, whose scholar he had been, and at the same time shows himself so thoroughly at home in the general question, that he is able to throw additional light on it by new and ingenious considerations and experiments. Harvey appears to have been pleased with Slegel’s production; for by and by he sends the Hamburger his new work on Generation, accompanied by an admirable letter, which has happily been preserved.[44] No one in reading that remarkable epistle could suppose that the pen which set it down was in the hand of a man in the 75th year of his age. The young men of 1628 and 1630, who had been educated in unbelief of the circulation, were now coming into possession of professorial chairs and places of distinction; and having long escaped from leading-strings and made inquiry for themselves, were beginning in many of the European universities to proclaim the better faith through further knowledge that had sprung up within them. Harvey had himself received the seeds of his discovery in Italy; but the fructifying mother was slow to recognize him whom she had so powerfully concurred to form. It was not till 1651 that Harvey’s views were in any way admitted beyond the Alps, when Trullius, a Roman professor, expounded and taught them. About the same time, John Pecquet,[45] of Dieppe, and Thomas Bartholin, the Dane,[46] men of original mind in the one case, of extensive learning and great research in the other, gave in their adhesion to the new doctrine, and spread it far and near by their writings. The victory for the circulation may finally be said to have been won, when Plempius, of Louvain, the old antagonist of Descartes on the subject, retracted all he had formerly written against it, convinced of its truth, as he so candidly informs us, by the very pains, he took to satisfy himself of its erroneousness, and publicly proclaimed his conversion: “Primum mihi hoc inventum non placuit,” says the worthy Plempius--“This discovery did not please me at all at first, as I publicly testified both by word of mouth and in my writings; but by and by, when I gave myself up with firmer purpose to refute and expose it, lo! I refute and expose myself, so convincing, not to say merely persuasive, are the arguments of the author: I examine the whole thing anew and with greater care, and having at length made the