42 APPENDIX. 



there. In consequence of this interruption, previously to the prussiate arriving at the 

 upper extremity of the duct, the discovery of the salt in the serum of the blood clearly 

 evinces that it was conveyed there by other channels. 



It is mentioned by Magendie, that he has seen, on pressing the lacteal branches so 

 as to discharge their contents in the direction of the trunks, that those branches would 

 again fill themselves after the animal's death. They have also witnessed these appear- 

 ances ; but they do not know of any similar observations to the following made on the 

 lymphatics, or of any evidence of the actual chemical presence of an article conveyed 

 after death into either of these systems from without. 



Four kittens were bled to what is commonly considered death. The blood ceased 

 to flow from the divided carotid, and voluntary motion was extinct. Prussiate of potass 

 in solution was then thrown into the abdomen. It appeared at the thoracic duct in five 

 and a half, five, fourteen, and twelve minutes respectively. In the two last, the great 

 vessels originating at the heart were secured by a common ligature. The blue colour 

 was in every instance perfectly distinct. 



In reasoning on the subject of absorption, the question has frequently arisen, whe- 

 ther the articles found in the living fluids exist there as chemical substances, or have 

 their chemical nature altered and animalized by the action of the vessels through which 

 they have entered the system. It was, however, deemed a curious subject of inquiry, 

 whether artificial chemical changes can take place in the fluids while they continue to 

 circulate in living vessels, and the ordinary actions of life go on. With a view of as- 

 certaining this point, they commenced by throwing prussiate of potass into the abdo- 

 men, and green sulphate of iron into the cellular tissue, in order to try whether the 

 well known result of their admixture, the prussian blue, would be produced in the ves- 

 sels. This, however, did not take place : and they resolved to repeat it by throwing 

 the sulphate, as the article of more difficult absorption, into the abdomen, where this 

 process went on with more facility, and the prussiate into the cellular substance. On 

 performing this, they were gratified by the striking result of a distinct and beautiful blue 

 in the thoracic trunk, and its contents, and in nearly the whole substance and surface 

 of the lungs. These viscera were preserved in spirits, and are now in their possession. 

 The blood threw up a coagulum of a strong blue colour, and the lymph and chyle from 

 the thoracic duct, threw down a blue deposit. Thus not only a foreign, but a pulveru- 

 lent substance could present its unnatural stimulus and circulate through the vessels, 

 and accumulate in the lungs, without preventing the actions of life from considerable 

 exertion, and without occasioning coagulation of the blood. The animal manifested some 

 difficulty of respiration before she was killed, but walked about without the least diffi- 

 culty, and uttered no cries, nor other signs of disturbance of its powers. In another 

 case, the urine and lungs were noted as exhibiting a blue colour. The other parts si- 

 milar to those above enumerated, are not described as being found coloured. In a 

 third, the fluid in the thoracic duct was blue, but not the other fluids examined, nor the 

 lungs. Two unsuccessful trials were also made. In another case the thoracic duct was 

 tied, and the same process repeated. A divided bluish green was here found in the 

 urine ; but neither the serum of the arterial blood, nor the lymph of the ductus tho~ 

 racicus, manifested the blue or green. 



Of tlte Mion of the Heart and Arteries. 

 NoteR. 



I. Of the Heart. The muscular fibres of the heart are more apparent in the foetus 

 than in the adult ; it only participates in the general paleness of muscular textures at 

 that epoch, although it is deeper coloured than they are. It also is entirely without fat at 

 this period. In old age the texture of the heart becomes softer and more flaccid than 

 in the young subject, and its parietes thinner : its cavities enlarge, especially the right, 

 and its surface is more charged with fat. 



The nerves of the heart have been a subject of interest with physiologists. Since 

 they were investigated by Scarpa opinions have been tolerably uniform respecting them; 

 and numerous observers have proved the general accuracy of his researches. The 

 cardiac nerves are chiefly derrived from the ganglia of the great sympathetic : a few 

 also come from the pneumo-gastric ; but these seem rather to inosculate with the for- 

 mer, than to go directly to the texture of the organ. The cardiac ganglion, situated 



