CIRCULATING SYSTEM. 337 



The structure of the lacteal and lymphatic vessels is si- 

 milar. They are composed of two coats, an internal and 

 external, the former being thin and smooth, the latter fibroin. 

 The extent of the absorbing power, however, is not the same 

 in both. The lacteals appear to be incapable of absorbing 

 any thing else but chyle. M. MAGENDI *, administered to 

 a dog diluted alcohol during digestion ; and, although he 

 was able to detect its presence in the blood, yet in the chyle 

 no traces of it could be perceived. The experiments of Sir 

 E. HOME, already quoted, and which have been repeated 

 by M. MAGENDif, (in reference to the use of the spleen,) 

 lead to the same results. The absorbing power of the lym- 

 phatics is not so limited. Dispersed throughout the whole 

 body, and destined to absorb occasionally every substance 

 of which it consists, fat, bone, the watery part of the bile, 

 urine, and faeces, when too long retained, they are like- 

 wise capable of taking up a variety of foreign substances, 

 when brought into contact with the orifices of their roots. 

 It is owing to the action of the lymphatics, that alcohol, 

 camphor, rhubarb, and a variety of other substances thrown 

 into the stomach, which the lacteals do not absorb, and 

 different substances rubbed on the skin, are conveyed into 

 the system. Attempts have been made to establish the 

 opinion, that absorption of foreign matter takes place inde- 

 pendent of either lacteals or lymphatics, since the blood 

 exhibits proofs of the entrance of such into the system, which 

 are not afforded by the contents of the thoracic duct. But 

 the connection which has been pointed out between the lac- 

 teal and lymphatic vessels and the veins, independent of 

 the thoracic duct, throws a considerable degree of doubt 

 over the supposition. 



The lacteals and lymphatics have been long known as the 

 absorbents in the mammalia. HUNTEK, HEWSON, and 



* Precis Elementaire de Physiologic, vol. ii. p. 168. f Ibid. p. 182, 



VOL. I. 



