OF THE ABSORBENT VESSELS. J 29 



from the substance of the " thoracic and abdominal viscera," in 

 short, from every part, at least, where there is moisture. a 



" Their origin is similar to that of the lacteals in the intestines, 

 so that the radicle of each lymphatic absorbs the fluid from the 

 surrounding spot, as from its territory, and propels it onwards. 



<e The lymphatics," like the lacteals, " have double valves, set 

 more or less thickly in different parts ; they almost all enter con- 

 globate glands," perfectly similar to the mesenteric, diffused 

 throughout the body, and aggregated in some situations, as in the 

 groins and axillae : "those lymphatics which are contiguous to each 

 other anastomose here and there, and those found on the surface 

 ot certain viscera, as the lungs, liver, &c., form a most beautiful 

 network." In the extremities, they run in two sets, one deep- 

 seated and accompanying the arteries, the other superficial and 

 accompanying the subcutaneous veins. 



" Besides other aids to their functions, evident from what has 

 already been said, no inconsiderable assistance is derived from 

 the combination of great strength with thinness of their coats 

 by which they are enabled to support a heavy column of quick-^ 

 silver. In the limbs, especially, the motion of the muscles, 

 pressing them on every side, is highly useful in increasing their 

 power." 



Dr. Carson argued that the thoracic vacuum, which is ex- 

 plained in the chapter on respiration, would not only draw the 

 blood along the veins, but draw it into their open mouths, thus 

 being an agent of absorption. He concluded that the blood of 

 the corpora cavernosa penis enters the veins in this way, but, 

 as the lymphatics only were believed the organs of absorption, 

 properly so called, when he first wrote, he had not a more extended 

 idea of the co-operation of the vacuum in producing venous 

 absorption. It must, however, evidently extend to every absorb- 

 ing vein, and if the veins absorb generally, as some now believe, 

 it must be general. As the great trunk of the absorbents ter- 

 minates in a vein, they must be circumstanced in this respect 

 exactly like veins, and equally subject to the influence of the 

 thoracic vacuum. Indeed, Dr. Barry, in a work quoted in the 

 chapter on respiration, found that while a cupping-glass was 

 applied over a wound to which poison was applied, no ab~ 



a " Mascagni, tab. i. ii. iii. 



T. Gottl. Haase, De vasis cutis et intestinorum absorbentibus, &c. Lips. 1786. 

 fol. tab. i." 



K 3 



