290 ABSORPTION LYMPH AND CHYLE. 



black introduced into the intestinal canal of animals, showed that although 

 the intestinal mucous membrane became of a deep black, this could easily be 

 removed by a stream of water and no carbonaceous particles could be dis- 

 covered in the mesenteric veins, the lacteals or the mesenteric glands. When 

 the carbon is used in the form of lamp-black, the particles are very minute 

 and rounded, and they do not present the sharp points and edges which 

 sometimes enable the grains of pulverized charcoal to penetrate the vessels 

 mechanically. 



VARIATIONS AND MODIFICATIONS OF ABSORPTION. 



Very little is known concerning the variations in lacteal or lymphatic ab- 

 sorption ; but in absorption by blood-vessels, important modifications occur, 

 due, on the one hand, to different conditions of the fluids to be absorbed, and 

 on the other, to differences in the constitution of the blood and in the con- 

 ditions of the vessels. 



The different conditions of the fluids to be absorbed apparently do not 

 always have the same influence in physiological absorption as in endosmotic 

 experiments made out of the body. Saccharine solutions of different densi- 

 ties confined in distinct portions of the intestinal canal of a living animal do 

 not present any marked variations in the rapidity of their absorption, and 

 they are taken up by the blood, even when their density is greater than 

 that of the blood-plasma. Solutions of potassium nitrate and of sodium sul- 

 phate, of greater density than the serum, which would, therefore, attract the 

 endosmotic current in an endosmometer, are readily taken up by the blood- 

 vessels in a living animal. Indeed, nearly all soluble substances, whatever 

 be the density of their solutions, may be taken up by the various absorbing 

 surfaces during life. The curare poison and most of the venoms are remark- 

 able exceptions to this rule. In a series of experiments upon the absorption 

 of curare, Bernard has shown that this poison, Avhich is absorbed so readily 

 from wounds or when injected under -the skin, generally produces no effect 

 when introduced into the stomach, the small intestine or the urinary bladder. 

 This result, however, is not invariable, for poisonous effects are produced 

 when curare is introduced into the stomach of a fasting animal. This pecul- 

 iarity in the absorption of many of the animal poisons has long been ob- 

 served ; and it is well known that the flesh of animals poisoned with curare 

 may be eaten with impunity. It is curious, however, to see an animal carry- 

 ing in the stomach without danger a fluid which would produce death if in- 

 troduced under the skin ; and the explanation of this is not readily apparent. 

 The poison is not neutralized by the digestive fluids, for curare digested for 

 a long time in gastric juice, or taken from the stomach of a dog, is found to 

 possess all its toxic properties. This may be shown by poisoning a pigeon 

 with curare drawn by a fistula from the stomach of a living dog (Bernard). 

 If the absorption of this poison be recognized simply by its effects upon the 

 system, it must be assumed that during digestion, it can not be absorbed by 

 the mucous membrane of the stomach and small intestine, notwithstanding 

 its solubility. 





