WILLIAM HARVEY 11 



the connection between the smallest arteries and the smallest veins, 

 for the microscope was not in such a stage of perfection as to 

 permit of much fine work in minute anatomy. It was not until the 

 invention of the compound microscope in 1675 that Leeuwenhoek 

 described blood corpuscles and the capillary circulation. In the first 

 chapter the author reviews some of the fantastic theories regarding 

 the functioning of heart and lungs. The heart was held to be the 

 great heat center of the body. The blood was sucked into it during 

 diastole and expelled from it during systole. The arteries cooled the 

 blood; the lungs fanned and cooled the heart. The term "spirits''^ 

 meant a great deal to Harvey's predecessors, but not to him. ^Xhe^ 

 word blood has nothing of grandiloquence about it, for ir^Igmfies a 

 substance which we have before our eyes and can touch; but before 

 such titles as spirit and calidum innatum (inherent heat) we stand 

 agape." , ^^ 



Chapter I, he continues: ^' .^^^ 



"When I first gave my mind to vivisections, as a means of discovering the 

 motions and uses of the heart, and sought to discover these from actual inspec- 

 tion, and not from the writings of others, I found the task so truly arduous, so 

 full of difficulties, that I was almost tempted to think, with Fracastorius, that 

 the motion of the heart was only to be comprehended by God. For I could 

 neither rightly perceive at first the systole and when the diastole took place, nor 

 when and where dilatation and contraction occurred, by reason of the rapidity 

 of the motion, which in many animals is accomplished in the twinkling of an eye, 

 coming and going like a flash of lightning; so that the systole presented itself to 

 me now from this point, now from that; the diastole the same; and then every- 

 thing was reversed, the motions occurring, as it seemed, variously and confusedly 

 together. * * * 



"At length, and by using greater and daily diligence, having frequent re- 

 course to vivisections, employing a variety of animals for the purpose, and collat- 

 ing numerous observations, I thought that I had attained to the truth, that I 

 should extricate myself and escape from this labyrinth, and that I had discovered 

 what I so much desired, both the motion and the use of the heart and arteries; 

 since which time I have not hesitated to expose my views upon these subjects, 

 not only in private to my friends but also in public, in my anatomical lectures 

 after the manner of the academy of old." 



He goes on to tell how his views pleased some, displeased others. 



He finds it advantageous to study the movement of the heart in 

 the cold-blooded animals — frogs, snakes and fishes. He ascertained 

 that the heart was a muscular organ, that its systole was the result 

 of muscular contraction. The contraction of the heart was more im- 

 portant than its dilitation. "During its contraction the heart becomes 

 erect, hard and diminished in size, so that the ventricles become 

 smaller and are so made more apt to expel their charge of blood. In- 

 deed, if the ventricle be pierced the blood will be projected forcibly 

 outward at each pulsation when the heart is tense." Harvey -shQwM__ 

 that the pulsation of the arteries depended upon the contraction of 

 the left ventricle. The contraction of the right ventricle propelled 



*The extracts which follow illustrate Harvey's style. The Motion of the 

 Heart and Blood, by William Harvey, can be procured in convenient form 

 in the Everyman's Library Series (E. P. Button «& Co., New York). This is 

 a reprint from the Sydenham Society's edition of 1847. 



