36 APPENDIX 



a degree, as to deposit it wheii heated, or on the addition of concentrated sulphuric acid. 

 Those appearances, however, are not constant, they are more generally met with in the 

 acute forms of dropsy. In some cases of rickets, the urine has been found saturated 

 to a high degree with phosphate of lime. Its character in diabetes is well known. 

 Blood is frequently found in the urine ; it gives this secretion more or less of a dark 

 colour and muddy sediment. Mucus is also met with in this fluid, during diseases 

 affecting either the kulnies, the raucous membrane of the bladder, or the prostate 

 gland. 



Of Absorption. 

 Note Q. 



L Of Absorption fram the Digestl-oe Canal It appears, from the experiments of Tie* 

 demann and Gmelin on absorption, that the lacteals take up the digested and dissolved 

 portions of alimentary substances, and convey them as a chyle through the thoracic 

 duct to the blood-vessels : but as odoriferous, colouring, and some saline substances, 

 are not absorbed by them, and yet are found in the blood of the vena portse, and in se- 

 creted fluids, it must necessarily follow, that there must be some other way than the 

 thoracic duct, by which they pass into the blood. 



The following- are the chief suppositions which have been offered in explanation of 

 the facts: " Either all the lacteals do not enter the thoracic duct, and part of them 

 join the veins which form the vena portae, and thus transmit their contents into the 

 blood of the vena portae ; or substances pass directly from the stomach and intestinal 

 canal into the veins ; or finally, both of these suppositions may be true." 



These physiologists found, that quicksilver injected into the absorbents of the intes 

 tinal canal easily reached the mensenteric veins and the vena portse, and this communi- 

 cation was found to take place in the mesentedc glands. By means of this communica- 

 tion they explain the appearance of streaks of a substance like chyle, which is perceiv- 

 ed in the blood of the vena portae after taking food a fact which has been frequently 

 observed by other anatomists. 



Though the passage of chyle into the vena portae, may be explained by this connec- 

 tion of the absorbents with the veins of the intestines, it 'would appear from the experi- 

 ments, that the passage of odorous colouring and saline substances, does not take place 

 in the same way. The presence of alcohol, gamboge, indigo, could never be detected 

 in the lacteals, or thoracic duct, though it was abundantly manifest in the blood of the 

 mesenteric veins, and in the vena portae. They therefore conclude, that the passage of 

 these substances must be effected through other channels, and that these channels must 

 be the radicles of the veins of the intestines. It was found, on examining blood taken 

 from a branch of the mesenteric vein of a dog, to which sulphuro-prussiate of potass 

 had been given, that no streaks of chyle were present, but the saline matter was per- 

 ceived. From this, and other experiments, they conclude that the veins of the intes- 

 tines appear particularly to absorb heterogeneous substances, such as those already par- 

 ticularized, whilst the lacteals take up nutritious matter ; and consequently, that sub- 

 stances taken into the digestive canal may pass into the mass of blood 1, through the 

 absorbents, and the thoracic duct; 2, through absorbents, which are united with veins 

 in the mesemeric gland; 3, through the radicles Or the commencement of the mesen- 

 teric veins which ultimately form the vena port*. 



, And it seems established by the experiments, that the vena portae receives chyle 

 from the absorbents, and other substances which are taken up from the intestinal 

 canal by the veins themselves, and as the blood of the vena portse, into which these 

 materials are conveyed, passes through the liver, this viscus must be regarded as an 

 organ of assimilation as well as of secretion. See the Note 01* the Functions of the 

 Liver. App. p. 25. 



II. Of Absorption in the Lung's. Professor Mayer, of Bonne, infers, from experi- 

 ments instituted in order to ascertain to what extent absorption takes place from the 

 lungs 



1. That animals support a considerable quantity of liquid injected into the lung's, 

 \vithout experiencing mortal symptoms from them ; but these injections should DC 

 performed by an opening made in the trachea. 



2. The symptoms of suffocation which arise from injections are not serious when 

 \ve inject pv.re water ; but they become so when thick fluids, for example, oil which 

 obstructs the aerial passages, or some chemical eolations, which inflame tho bronchial 

 surfaces, ftre employed in this manner. 



