290 Banister and Pulmonary Circulation 



able that Servetus knew of his Arabic predecessor/ nor has any historical link 

 been established between Ibn an-NafIs and Columbus. Whether, on the other 

 hand, any connection existed between Servetus and Columbus is a question 

 still open for debate. 



No such difficult questions of historical priority confront us when we read 

 the paragraphs in Banister's Historie of Man that deal with pulmonary cir- 

 culation. Not only does he quote his authority, Columbus, but most of the 

 latter's passages concerning circulation can be found in literal translation in 

 Banister's text. Yet Banister's arrangement is somewhat different; and in order 

 to understand the task he had to solve, we must briefly review Columbus' 

 argument. 



What we now call the pulmonary circulation (neither Columbus nor Banis- 

 ter knew that all the blood had to pass through the lungs) is described by 

 Columbus in two different parts of his De Re Anatomica and under slightly 

 different points of view. In book VII, "On the Heart and Arteries," he develops 

 his thesis in refutation of the traditional theory, while in the chapter "On the 

 Lung" (book XI, ch. 2) he gives full emphasis to his claim of having discovered 

 a new "use" of the lung. 



The traditional theory which Columbus attacked presented itself about as 

 follows: From the right ventricle of the heart, blood passed through the septum 

 into the left ventricle. On this passage it became thin on account of the genera- 

 tion of vital spirits which the arteries carried through all parts of the body. 

 The pulmonary artery (the "arterial vein" in Galenic terminology) carried 

 blood to the lungs for their nourishment. In the pulmonary vein ("venous 

 artery") fumes were carried from the left ventricle to the lung. This is not a 

 complete picture of the original Galenic theory, but it gives the points which 

 Columbus attacked. "For the blood," he says, "is carried through the arterial 

 vein to the lung and is there made thin; then, together with air it is carried 

 through the venous artery to the left ventricle of the heart: which nobody 

 has hitherto noticed or left in writing: although greatest attention should be 

 paid to it by everybody."" The size of the pulmonary artery suggests that the 

 blood which it carries is not only for the nourishment of the lung, but also 

 for alteration. Dissection and vivisection, moreover, prove that the pulmonary 

 vein contains blood, not fumes. 



According to the traditional theory, the use of the lung was twofold. 

 Through inspiration and expiration the vocal organs received the necessary 

 air; and by carrying air to the heart, the lung served the latter, the seat of the 

 "innate heat." Columbus acknowledges these views as correct. But he claims 

 to have discovered an additional "use" of which no anatomist before had even 

 dreamt. This new use is the elaboration of the vital spirit in the lung; and 

 though he variously alludes to it in the part dealing with the heart and ar- 

 teries, the doctrine is fully stated in the chapter "On the Lung." In this chapter, 

 then, we find another and more comprehensive formulation of the pulmonary 

 circulation and we may quote it in Banister's almost literal translation. 



