Circulation of the Blood 119 



I shall elsewhere state my views of the lacteal veins 

 when I treat of the milk found in different parts of 

 new-born animals, especially of the human subject ; 

 for it is met with in the mesentery and all its glands, 

 in the thymus, in the axillae, also in the breasts of 

 infants. This milk the midwifes are in the habit of 

 pressing out, for the health, as they believe, of the 

 infants. But it has pleased the learned Riolanus, not 

 only to take away circulation from the blood contained 

 in the mesentery ; he affirms that neither do the vessels 

 in continuation of the vena cava, nor the arteries, nor 

 any of the parts of the second and third regions, admit 

 of circulation, so that he entitles and enumerates as 

 circulating vessels the vena cava and aorta only. For 

 this he appears to me to give a very indifferent reason : l 

 " The blood," he says, " effused into all the parts of the 

 second and third regions, remains there for their 

 nutrition ; nor does it return to the great vessels, unless 

 forcibly drawn back by an extreme dearth of blood in 

 the great vessels, nor, unless carried by an impulse, 

 does it flow to the circulatory vessels." 



That so much of the blood must remain as is 

 appropriated to the nutrition of the tissues, is matter 

 of necessity ; for it cannot nourish unless it be 

 assimilated and become coherent, and form substance 

 in lieu of that which is lost ; but that the whole of the 

 blood which flows into a part should there remain, in 

 order that so small a portion should undergo transforma- 

 tion, is nowise necessary ; for no part uses so much blood 

 for its nutrition as is contained in its arteries, veins, 

 and interstices. Nor because the blood is continually 

 coming and going is it necessary to suppose that it 

 leaves nothing for nutriment behind it. Consequently 

 it is by no means necessary that the whole remain in 

 order that nutrition be effected. But our learned 

 author, in the same book, where he affirms so much, 

 appears almost everywhere else to assert the contrary. 



1 Enchirid. lib. iii, cap. 8. 



