"make a cut in the trachea of a living dog, forcibly fill the lungs with air by means of a bellows and, when they have been distended, apply a firm ligature, on opening the chest shortly after, he would find great abundance of air in the lungs, up to their outermost tunic, but none at all in the venous artery or in the left ventricle of the heart. If in the living dog the heart drew air out of the lungs or the lungs transmitted it, much more ought they to do so in this experiment. Who, indeed, could doubt that even in a dissection, if the lungs of a dead body had been inflated, air would enter at once, as aforesaid, did any passages exist?"[71] Yet we have found Aristotle, more than nineteen centuries before Harvey, recognizing that no passages are needed for the transfer of air out of the windpipe, and saying, of the channels from the heart, that "it is by contact that they receive the breath[72] and transmit it to the heart."[73] Moreover, sixty-nine years before Harvey's publication Columbus had repeatedly recommended the experiment of opening the venous artery[20] in a living dog and noting that the "said venous artery" is full of blood, not of air or fumes. But Columbus held this observation rather to confirm than to disprove his doctrine that the blood in the venous artery is imbued with vital spirits derived in the lungs from the substance of the air. Indeed, he goes so far as to call the contents of this vessel "modified blood and air."[74] In this matter the earlier observer, Columbus, shows keener insight than the later, Harvey. Decidedly, however, the stage waits for the chemists, despite Harvey's poor opinion of them. Despite that poor opinion, too, Harvey himself turns to making chemical conjectures in the next passage of his note-book, to the study of which latter we will now return. The passage is as follows:-- "Conclusion. Opinion of W. H. "In animals in which lungs are fleshy and full of blood these concoct the blood, seeing that spirits and blood are one thing, in the same way that the liver does and by reason of the same arguments; indeed, the lungs may rather detain fatty and oleaginous vapor by a cooling process, as oil or balsam or nutritious fat is cooled in alembic and serpentina"[75]--