266 DIGESTION. 



with which they reappear in the urine or in the pulmonary 

 exhalation. 



What are the substances which, according to these experi- 

 ments, may be directly absorbed by the blood-vessels of the 

 stomach and intestine ? Among these numerous and, at first sight, 

 very various matters, we meet, in the first place, with certain 

 tolerably soluble salts, which, whether noxious or innoxious to the 

 animal organism, experience no essential changes whilst within it, 

 and do not exhibit any great affinities towards any constituents of 

 the animal body, namely, all the neutral alkaline salts, whose acid 

 shows no peculiar tendency to enter into special combinations 

 with other matters. To this class, therefore, belong the chlorides 

 of sodium and potassium, iodide and bromide of potassium, the 

 alkaline phosphates, sulphates, chlorates, nitrates, borates, and 

 arsenates, yellow prussiate of potash, sulphocyanide of potassium, 

 and the combinations of the alkalies with non-nitrogenous organic 

 acids. A second group of those substances which are especially 

 resorbed by the intestinal capillaries, are the acids, both mineral 

 and organic. A third group consists of alcohol, ether, wood-spirit, 

 and fusel oil (Schlossberger)*. A fourth group contains many 

 volatile oils, including the non-oxygenous as well as the oxygenous 

 and sulphurous oils, as, for instance, camphor, oil of radish, oil of 

 asafretida, &c. ; to these we may probably also add, combustible 

 and natural odoriferous substances, as musk and the constituents 

 of DippeFs animal oil, &c. A fifth group comprises several 

 alkaloids, whether volatile or non-volatile, as, for instance, strych- 

 nine, brucine, morphine, theme, nicotine ; and, finally, there remain 

 to be enumerated certain pigments, which cannot be detected in 

 the chyle, although they may be recognised in the urine, as, for 

 instance, the pigment of alkanna, of gamboge, whortleberries, black 

 cherries, rhubarb, logwood, madder, litmus, cochineal, sap-green, 

 and tincture of indigo. 



The great diversity of the substances above enumerated would 



make it appear difficult, if not impossible, to discover in them any 



common aggregation of properties by which their capacity for 



absorption through the blood-vessels might be influenced ; but 



certain other matters, which far exceed in solubility many of 



those already described, do not, as it would appear from direct 



.experiments, show the slightest disposition to enter through the 



capillaries into the blood, although they are very readily absorbed 



by the lymphatics, or else, notwithstanding their great solubility, 



* Arch. f. physiol. Ileilk. Bd. 9, S. 267. 



