30
HARVEY AND GALEN
by the occasional imperfection of the ventricular septum in the lower animals and by anatomical facts which I cannot enter upon. The same is true of the supposed anasto- moses between veins and arteries which Galen saw must somehow exist, though of course he was quite ignorant of capillaries. Even Harvey concluded from deduction, not from actual observation, that the terminal arteries and terminal veins were connected. Galen’s views of the heart and the motion of the blood have often been expounded and discussed. It is, therefore, unnecessary to go fully into them. I only desire to show that his methods of investiga- tion were perfectly sound, though they led to an erroneous conclusion. His sources of knowledge on the subject were - — (i) Dissection of a great variety of animals, mammalia (including at least once an elephant), birds, fishes, and reptiles. He says cautiously that he did not dissect such creatures as gnats, flies, bees, ants, and worms, because, seeing what mistakes anatomists had made in dissecting larger animals, he thought they would be likely to go still more wrong in the case of these small creatures. (2) Elabo- rate dissections, in the modern way, continually repeated, of those animals most resembling men, especially apes. (3) Observation of the heart and vessels in living animals which he opened for the purpose. He speaks, also, more than once of the case of a boy in whom the chest walls were deficient from the results of an accident, so that the movements of the heart could be seen. (4) Numerous ex- periments on living animals, made in his time with less reserve than at the present day. These experiments, though not always leading to correct conclusions, were extremely well contrived and quite scientific in their plan.
Of course Galen had a large body of anatomical know- ledge behind him, derived from the Alexandrian anatomists and their successors, but he never quotes any of their state- ments as authorities, relying entirely on his own observa- tions and demonstrations. Had he quoted those anatomists who had actually dissected the human body, he would probably have often been more correct, according to modern
