90 



MOTION OF THE CHYLE. 



blood-vessels. 



that if into a tube, a b,Fig. 29, through which a current of water is stead- 



ily flowing, another tube, c d, opens, its 

 more distant end being in communication 

 with a reservoir of water, e, through this 

 tube a current will likewise be establish- 

 ed, and the reservoir be emptied of its 

 contents. The effect is still greater, as 

 Bernouilli demonstrated, when the main 

 current is flowing toward the wide end 

 of a conical pipe. Moreover, the lacteal 

 tubes are elastic, and furnished with valves, 

 which open to let the fluid pass toward 

 the veins, but close in the opposite way. 



Principle of venturi. This valvular mechanism renders available 



any pressure arising either from the contractility of the vessels them- 

 Mechanism for selves, or from those various muscular movements, respira- 

 transfemng torv or voluntary* which affect the abdominal walls. The 



chyle from the J , . f 



viiius to the manner of introduction of the great lacteal trunk the tho- 

 racic duct at the angle of junction of the left subclavian and 

 f. DO. jugular veins, is also very felicitous, for the suc- 



tion force of those large vessels is there conjoin- 

 ed, and the effect is at a maximum. The con- 

 trol of the blood motion on the chyle motion is 

 obvious from this, that as soon as the circula- 

 tion stops the chyle stops, and this not so much 

 from the engorgement of the venous trunks, 

 which renders it difficult for the chyle to make 

 its way into them, as from the cessation of that 

 tractile force, which solicits the chyle to move 

 into the blood. 



Fig. 30 represents the position and course of 

 the thoracic duct, and its manner of introduction 

 of the chyle into the blood circulation. (Wil- 

 son.) 



1, Arch of aorta ; 2, thoracic aorta ; 3, abdom- 

 inal aorta ; 4, arteria innominata, dividing into 

 right carotid and right subclavian arteries ; 5, 

 left carotid ; 6, left subclavian ; 7, superior cava, 

 formed by the junction of, 8, the two vena? in- 

 nominata?, and these* by the junction, 9, of the in- 

 ternal jugular and subclavian on each side ; 10, 

 the greater vena azygos ; 11, the termination of 

 The thoracic duct. the lesser in the greater vena azygos ; 12, recep- 



