736 PHILOSOPHICAL TRANSACTIONS. [aNNO \672, 



Some Annotations hy Dr. Walter Needham, on a Discovery pretended 

 to have been made by M. Pecquet, of a Communication betiveen the 

 Ductus Thoracicus and the Inferior Vena Cava. N" 85, p. 5007 . 



The relation itself of that pretended discovery, as it is to be found in the 

 Journal des Sqavans of Feb. 8, 1672. 



Great part of this paper consists of arguments to show the necessity of the 

 chyle being conveyed into the blood by other channels than that by which the 

 thoracic duct pours its contents into the subclavian vein. Among other reasons 

 it is urged, that the orifice of that duct at its insertion into the aforesaid vein is 

 not sufficiently large for allowing all the chyle to pass, which should be con- 

 veyed into the blood. To this Dr. Needham replies, that what is sufficient or 

 not sufficient must be judged of by nature and not by us. Yet, adds he, if we 

 consider the time that is spent in carrying the chyle up into the blood, it is easy 

 to believe that a much greater quantity of liquor may be discharged by that duct 

 than is usually pretended to. But passing over the imaginary difficulties raised 

 by M. Pecquet, and the answers thereto, we shall proceed to the experiments 

 by which the pretended new communication is supposed to be proved. 



The observations made in the beginning of this year in his majesty's library, 

 by searching carefully the passage of the ductus thoracicus in the body of a 

 woman, have shown (says Mons. P.) that these difficulties are well grounded. 

 For it has been found by divers experiments, made about this matter, that there 

 ascends at least as much chyle through the trunk which is beneath the heart, 

 as there descends through that which is above it.* 



These experiments have appeared considerable, as they confirm those which 

 were also made by the same Royal Academy of Sciences about five years since, 

 and which were inserted in the 7th Journal des Sqavans 1667.^ But this last 

 experiment has been more clear and ample than the first, in that the communi- 

 cation which the first time appeared to be only with the left emulgent vein, has 

 been found this second time not only with this vein but also with the two lum- 

 bar veins, which are inserted in the trunk of the inferior vena cava. 



DR. NEEDHAM's annotations. 



<Cln the oiigindl these annotations are printed in columns by the side of the above relation.) 



* What those experhnents are we should be glad to know. But the experiment of l667 (if I 

 rightly remember it) was only a lusus naturae, found by M. Pecquet ; which I therefore call so, be- 

 cause neitlier he nor any one else has fou»d it since; whereas the vasa lactea, and the ways of order- 

 ing tliem are so well known, that, if any such thing were, it could not long be hid. ' 



t See No. 25, p. l63, of this vol. of the Abridgement. 



