HEART AND BLOOD. 19 



arteries must appear obscure, or inconsistent or even impossible 

 to him who carefully considers the entire subject; it will be 

 proper to look more narrowly into the matter; to contemplate 

 the motion of the heart and arteries, not only in man, but in 

 all animals that have hearts ; and further, by frequent appeals 

 to vivisection, and constant ocular inspection, to investigate and 

 endeavour to find the truth. 



CHAPTER I. 



THE AUTHOR'S MOTIVES FOR WRITING. 



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 inspection, and not from the writings 

 of others, I found the task so truly arduous, so full of difficul- 

 ties, 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 when 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 sys- 

 tole presented itself to me now from this point, now from that; 

 the diastole the same ; and then everything was reversed, the 

 motions occurring, as it seemed, variously and confusedly to- 

 gether. My mind was therefore greatlyunsettled, nor did I know 

 what I should myself conclude, nor what believe from others ; 

 I was not surprised that Andreas Laurentius should have said 

 that the motion of the heart was as perplexing as the flux and 

 reflux of Euripus had appeared to Aristotle. 



At length, and by using greater and daily diligence, having 

 frequent recourse to vivisections, employing a variety of animals 

 for the purpose, and collating 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, 



