128 Circulation of the Blood 



not a little both of time and labour to the inquiry ; but 

 I have never succeeded in tracing any connexion be- 

 tween arteries and veins by a direct anastomosis of 

 their orifices. I would gladly learn of those who give 

 so much to Galen, how they dare swear to what he 

 says. Neither in the liver, spleen, lungs, kidneys, nor 

 any other viscus, is such a thing as an anastomosis to 

 be seen ; and by boiling, I have rendered the whole 

 parenchyma of these organs so friable that it could be 

 shaken like dust from the fibres, or picked away with a 

 needle, until I could trace the fibres of every sub- 

 division, and see every capillary filament distinctly. 

 I can therefore boldly affirm, that there is neither any 

 anastomosis of the vena portse with the cava, of the 

 arteries with the veins, or of the capillary ramifications 

 of the biliary ducts, which can be traced through the 

 entire liver, with the veins. This alone may be observed 

 in the recent liver : all the branches of the vena cava 

 ramifying through the convexity of the liver, have their 

 tunics pierced with an infinity of minute holes as is a 

 sieve, and are fashioned to receive the blood in its 

 descent. The branches of the porta are not so con- 

 stituted, but simply spread out in subdivisions ; and the 

 distribution of these two vessels is such, that whilst 

 the one runs upon the convexity, the other proceeds 

 along the concavity of the liver to its outer margin, and 

 all the while without anastomosing. 



In three places only do I find anything that can be 

 held equivalent to an anastomosis. From the carotids, 

 as they are creeping over the base of the brain, 

 numerous interlaced fibres arise, which afterwards form 

 the choroid plexus, and passing through the lateral 

 ventricles, finally unite and terminate in the third sinus, 

 which performs the office of a vein. In the spermatic 

 vessels, commonly called vasa praeparantia, certain 

 minute arteries proceeding from the great artery adhere 

 to the vense prseparantes, which they accompany, and 

 are at length taken in and included within their coats, 



