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commemoration address, now known as the Harveian Oration. 

 Harvey did more than discover the circulation of the blood ; he 

 demonstrated, by the experimental method, that the blood moves in 

 a circle, that the movement of the blood is due to the mechanical 

 action of the heart as a pump, that systole is an active contract ion of 

 the heart and diastole a passive act of dilatation. He gave a ferae 

 theory of the pulse. For all time he set the method, viz., that of 

 experiment and induction, which has led to all modern progress in 

 physiology. He tells us both his motives and his methods. 



" 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 difficulties, that I was 

 almost tempted to think, with Frascatorius, that the motion of the heart was only to be 

 comprehended by God. . . . 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. . . " 

 (Chap. I.) 



Although Harvey was quite clear that the arteries and veins do 

 communicate, it was reserved for Malpighi, by the use of the micro- 

 scope, in 1664— seven years after Harvey's death — to demonstrate on 

 the lung of a frog the passage of the blood from arteries into veins by 

 means of the capillaries. 



GASPAR ASELLI. 



1580-1626 (aet. 46). 



UP to nearly the end of the first quarter of the seventeenth century 

 the only vessels known to Anatomists were arteries and veins. 

 There was born at Cremona, in 1580, one Gaspar Aselli, 

 Professor in Pavia, and surgeon in Milan, who in 1622 accidentally 

 made a great discovery, viz. the " lacteal veins " or lacteals. The work 

 was published posthumously in 1627, through the liberality of Claude 

 Nicolas de Pieresc, a Seigneur of the old regime and a patron of 

 science, — under the direction of A. Tadinus and Senator Septalinus. 

 These colleagues of Aselli were witnesses of the original discovery. 

 The work is entitled De Lactibus sice lacteis Vents &c. Dissertatio 

 (Mediolani 1627). Besides the four remarkable plates, with the white 

 lacteals on a red ground, the natural colour of the parts, it contains 

 the portrait of the author here reproduced, which is taken from the 

 copy of this work in the Library of the Eoyal College of Surgeons of 

 England. It is said to be the first work in which block printing 

 is used for the purpose of illustration. 



Aselli tells us how he made the discovery accidentally on July 

 23rd, 1622. While dissecting a dog, which had been fed a few hours 



D 



