164 PHYSIOLOGY CHAP. 



to the veins, through the anastomosis, which he termed the " rasa 

 in capillamenta resoluta," to every part of the body ; this perpetual 

 forward movement of the blood from the vena cavae to the right 

 heart, thence to the lungs, from the lungs to the left heart, and 

 from the left heart to the arteries was termed by him Circulcdio. 

 He was the first to recognise the arterial structure of the 

 pulsating vessel, which arises in the right ventricle, and was 

 designated by Galen the vena arteriosa, and the venous structure 

 of the non-pulsating vessels, which had been known as the arteria 

 venosa. He also recognised that the blood in the arteries stands 

 at far higher pressure than that in the veins, and that in its 

 passage from the one to the other the capillary anastomoses offer 

 greater or less resistance according to the degree of their contraction 

 or dilatation. 



Again, in his books De plantis, which appeared twelve years 

 after the Questiones peripateticae, and would alone suffice to 

 bring him undying fame as a forerunner of Linnaeus, Cesalpinus 

 affirmed that the blood " per venas duci ad cor, et per arterias in 

 universum corpus distribui." 



In 1593 Cesalpinus published his Questionum medicarum 

 libri II., giving the experimental evidence for his theories. He 

 observed that when in a living animal a vein was exposed, 

 ligatured, and soon after cut below the ligature in the direction 

 of the capillaries, the blood which first flowed out was darker in 

 colour, and that which followed lighter. From this observation 

 he deduced with great acumen the physiological function of the 

 anastomoses that occur in almost every organ between the veins 

 and arteries, maintaining " venas cum arteriis adeo copulari 

 osculis, ut, vena secta, primum exeat sanguis venalis nigrior, deinde 

 succedat arterialis flavior, ut plerurnque coiitingit." 



He founded a second experimental proof of the circulation on 

 the fact that in any part of the body the ligatured vein swells 

 between the ligature and its capillary origin, and not between the 

 heart and the ligature, as would be the case according to Galen's 

 notion, " intercepto enim meatu, non ultra datur progressus ; 

 tumor igitur venarurn citra vinculum debuisset fieri." 



Notwithstanding this brilliant experimental evidence for the 

 doctrine of the circulation, as first brought forward by Cesalpinus, 

 certain writers, among them the celebrated Haller, maintained 

 that while the Aretine philosopher was undoubtedly acquainted 

 with the circulation, he recognised it solely for the sleeping, and not 

 for the waking state. This is founded on a quite erroneous inter- 

 pretation of a passage in which Cesalpinus admits a certain 

 regurgitation of blood from the arteries towards the heart during 

 the waking state. Ceradini, with convincing logic, has shown the 

 absurdity of Haller's contention, to be explained perhaps by the 

 fact that as a member of the Koyal Society of London he might 



