44 Harvey and the [lect. 



believed to pass through not the septum but the lungs. Harvey 

 saw that all the reasons for thinking that any of the contents 

 of the ventricle so passed, were equally valid for thinking that 

 all passed, and that the latter view alone was consonant with 

 the facts. 



This new view, new in reality, though having so much 

 resemblance to old ones that Harvey speaks of it as one " to 

 " which some, moved either by the authority of Galen or 

 " Columbus or the reasonings of others will give their ad- 

 " hesion," led him at once to another conception which however 

 " was so new, was of so novel and unheard of a character that 

 " in putting it forward he not only feared injury to himself from 

 " the envy of a few, but trembled lest he might have mankind 

 " at large for his enemies." This new view consisted simply in 

 applying to the greater circulation the same conclusions as 

 those at which he had arrived in regard to the lesser circulation. 



It is important to note that to this new view he was guided 

 by distinctly quantitative considerations. He argued in this way. 

 At each beat of the heart a quantity of blood is transferred 

 from the vena cava to the aorta. Even if we take a low 

 estimate (he had made observations with a view to determining 

 the exact amount but he leaves this aside for the present as 

 unessential), say half an ounce, or three drachms, or only one 

 drachm, and multiply this by the number of beats, say in half- 

 an-hour, we shall find that the heart sends through the arteries 

 to the tissues during that period as much blood as is contained 

 in the whole body. It is obvious, therefore, that the blood 

 which the heart sends along the arteries to the tissues cannot 

 be supplied merely by that blood which exists in the veins as 

 the result of the ingesta of food and drink ; only a small part 

 can be so accounted for ; the greater part of that blood must be 

 blood which has returned from the tissues to the veins ; the 

 blood in the tissues passes from the arteries to the veins, in 

 some such way as in the lungs it passes from the veins (through 

 the heart) to the arteries ; the blood moves in a circle from the 

 left side of the heart, through the arteries, the tissues and the 

 veins to the right side of the heart, and from thence through 

 the lungs to the left side of the heart. 



