HARVEY AND EXPERIMENTAL OBSERVATION | 51 
of either observations or experiments by him). He also laid 
hold of a still more important conception, vis., that some of 
the blood passes from the left side of the heart through the 
arteries of the body, and returns to the right side of the heart 
by the veins. But a fair consideration of the claims of these 
men as forerunners of Harvey requires quotations from their 
works and a critical examination of the evidence thus adduced. 
This has been excellently done by Michael Foster in his Lec- 
tures on the History of Physiology. Further considerations 
of this aspect of the question would lie beyond the purposes 
of this book. 
At most, before Harvey, the circuit through the lungs had 
been vaguely defined by Galen, Servetus, Columbus, and 
Cesalpinus, and the latter had supposed some blood to pass 
from the heart by the arteries and to return to it by the veins; 
but no one had arrived at an idea of a complete circulation 
of all the blood through the system, and no one had grasped 
the consequences involved in such a conception. Harvey’s 
idea of the movement of the heart (De Afotu Cordis) was new; 
his notion of the circulation (ef Sanguinis) was new; and 
his method of demonstrating these was new. 
Harvey’s Argument.—The gist of Harvey’s arguments is 
indicated in the following propositions quoted with slight 
modifications from Hall’s Physiology: (1) The heart pas- 
sively dilates and actively contracts; (II) the auricles contract 
before the ventricles do; (III) the contraction of the auricles 
forces the blood into the ventricles; (IV) the arteries have 
no “pulsific power,” i.e., they dilate passively, since the pul- 
sation of the arteries is nothing else than the impulse of the 
blood within them; (V) the heart is the organ of propulsion 
of the blood; (VI) in passing from the right ventricle to the 
left auricle the blood transudes through the parenchyma of 
the lungs; (VII) the quantity and rate of passage of the blood 
peripherally from the heart makes it a physical necessity that 
