CIRCULATION OF THE BLOOD. 103 



ceeded in making such anastomoses as he imagines, sensible to 

 the eye. 



I have myself pursued this subject of the anastomosis with 

 all the diligence I could command, and have given not a little 

 both of time and labour to the inquiry ; but I have never suc- 

 ceeded in tracing any connexion between 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 subdivision, and see every capillary filament 

 distinctly. I can therefore boldly affirm, that there is neither 

 any anastomosis of the vena porta? 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 constituted, but 

 simply spread out in subdivisions ; and the distribution of these 

 two vessels is such, that whilst the one runs upon the con- 

 vexity, 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 prseparantia, certain 

 minute arteries proceeding from the great artery adhere to 

 the venae prseparantes, which they accompany, and are at length 

 taken in and included within their coats, in such a way that 

 they seem to have a common ending, so that where they ter- 

 minate on the upper portion of the testis, on that cone-shaped 



