172 PHYSIOLOGY CHAP. 



contents not to the liver, as had been supposed by Aselli, but to 

 a large vessel which he rediscovered after Eustachius, the thoracic 

 duct, which empties itself into the subclavian vein. Two years 

 later, the lymphatics of the liver were discovered by a Swede, 

 Eudbeck, who recognised that they, too, emptied their contents 

 into the thoracic duct. Finally, in 1652, the celebrated Danish 

 anatomist, T. Bartholin, discovered the same vessels in every part 

 of the body, and found that they all flowed, with the chyliferae, 

 into the thoracic duct. In order to extend the theory of the 

 circulation, which he attributed to Harvey, he brought out a new 

 edition of his Anatomy, ad sanguinis circulationem reformata, 

 in the legitimate conviction that he had found a new and 

 invaluable argument, even though an indirect one, in its 

 favour. 



" Eiolan," adds Ceradini, " Eiolan himself, the adherent of 

 every old tenet and opponent of all that was new, on this occasion 

 held back the darts of his criticism, that he might not blunt them 

 against the weight of i'acts. Harvey alone rejected chyle as well 

 as lymph vessels, together with the function of the thoracic duct, 

 and died, without retracting his views, in 1658, six years after 

 Bartholin." 



VII. One last decisive step was wanting to complete the new- 

 doctrine and bring it into prominence the discovery of the 

 capillary vessels and direct observation of the circulation through 

 these from the arteries to the veins. " Supererat," as said Haller, 

 " ut ipsis oculis circuitus sanguinis subjiceretur." 



Galen, as already stated, was the first to postulate a direct 

 connection of the arterial and venous blood in the organs, figuring 

 it as a direct anastomosis or conjunction of the two sets of vessels. 

 This did not correspond with the notion of Cesalpinus, who 

 certainly admitted that the communications were made by " per 

 vasa non desinentia, ulterius trasmeantia" or "per vasa in 

 capillamenta resoluta " (which Harvey translated into " per carnis 

 porositates "), thus divining the existence of that new order of 

 vessels, joining the arteries with the veins, which were subsequently 

 termed capillaries. 



Marcello Malpighi, in 1661, was the first to see the movement 

 of the blood in the capillaries of the frog's lung under the micro- 

 scope. He exclaims, " Talia mihi videre contingit, ut non im- 

 merito illud Homeri usurpare possim ad rem praesentem melius : 

 magnum certum opus oculis video " (Fig. 48). 



After Malpighi, Leuwenhoek, Cooper and Haller tried in vain 

 to repeat this observation on warm-blooded animals. The first 

 who succeeded was Lazzaro Spallanzani, who bethought himself of 

 using the hen's egg during the development of the embryo. The 

 enthusiastic words in which the great physiologist records his 

 discovery are pleasant reading : " Long have I been burning with 



