vr CIRCULATION OF BLOOD: ITS DISCOVERY 169 



of the experiments and ideas of Cesalpinu.s. When the arm is 

 tightly ligatured, as for an amputation, the arterial pulse disappears 

 at the periphery, while centrally the arteries pulsate more strongly 

 and swell up. The hand and arm become cold after a time. 

 When the arm is ligatured loosely, as for blood-letting, the arm 

 swells below the ligature, and the veins become prominent and 

 varicose. Above the ligature, on the other hand, they are invisible. 

 Tight ligatures impede the flow of blood through the arteries, a 

 loose one only blocks it in the veins. The blood, therefore, passes 

 from the arteries into the veins. In this Harvey, in slightly 



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Fi(i. 47. Reproduction of two first figures in Harvey's work (edition, 1(339, ex officina Joannis 

 Mitii-i', Ludguni Batavorum). Fig. 1 is an exact imitation of the figure in the De renarum ostiolis 

 of Fabriciiis. The arm is bandaged at AA, as for bleeding. The turgid veins are seen, with 

 swellings at B, C, D, E, F, caused by the valves. These occur not merely at the points of 

 bifurcation (E, F), but elsewhere (C, D). Fig. 2 represents the same arm, from which the 

 blood lias been expelled by pressure with the finger from to H. The vein between // and 

 is now obliterated, because at the point there is a valve, which prevents the blood from 

 flowing back to H, and at H the compression of the finger impedes the passage of the blood from 

 the peripheral veins. 



different words, repeats the conclusions of Cesalpinus : " Apparet 

 qua de causa in phlebotomia . . . supra sectionern ligamus, non 

 infra." The conclusion that the blood flows to the several organs 

 in much larger quantity " quam nutritioni sumciens sit," is again 

 taken from Cesalpinus, who described as " alinientum iiutritivum " 

 what is brought by the blood to nourish the organs, as " alimentum 

 auctivum " what returns to the heart, after passing from the 

 arteries to the veins by the capillaries. 



The demonstration of the third point is founded entirely on 

 the physiological function of the valves of the veins. Harvey 

 treats this point with great subtlety, since his chief concern is to 



