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read Harvey's works, and especially such a sentence as I have quoted as to the true method of research, could possibly have accepted this statement, for few better pieces of investigation are to be found in the whole annals of scientific discovery than his. He opened the pericardium, he observed the heart's movements, he cut into the organ and saw it squeeze the blood out, he then opened the arteries into which he believed the blood to pass, and witnessed the crimson stream ejected. He proposed to himself experiment after experiment until he had solved the problem of the circulation. No theoretic argument was his who had dissected every animal within his reach; for reptiles, fishes, insects were alike familiar to him. His powers of observation are also seen by his not forgetting to make use of cases in the human subject, for in an example of aneurism of the subclavian artery, he noticed the different sizes of the corresponding pulses of the wrists. Besides, he himself knew what a deduction was as opposed the method he had been pursuing, for he declared that if his discovery were true, then certain other truths might be deduced from it. He says "these truths, if proven, are not without their use in
