ARTIFICIAL CIRCULATION. 335 



APPENDIX 



Artificial Circulation through Isolated Organs. — Tn order to 

 study the effects of alterations in the blood, and the action of 

 various poisons upon the walls of the vessels themselves, with 

 entire exclusion of the nervous system, Ludwig and Mosso have 

 kept up artificial circulation in the kidney and the liver. In 

 removing these organs great care is taken not to wound them, 

 and the diaphragm is removed along with the liver. In 

 experimenting on the kidney large dogs were employed. The 

 carotids were first opened, and blood allowed to flow until 

 convulsions began. The artery was then closed for some time, 

 during which the blood was defibrinated and part of it put into 

 a fiask, so as to be ready to wash out all the coagulable blood 

 from the kidney. The carotids were now opened a second time, 

 and as much blood as possible got from them by pressure on 

 the abdomen, &c. As soon as the animal became insensible 

 the abdomen was opened, the renal artery was then compressed 

 just above its bification, so as to prevent any air getting into it, 

 and a glass cannula was introduced into the main artery; 

 another cannula was put into the. renal vein. All the small 

 vessels which communicate with adjacent parts were ligatured, 

 and the kidney was then removed. Before connecting the 

 cannula in the renal artery with the apparatus for artificial 

 circulation, it was carefully filled by means of a fine pipette 

 with defibrinated blood, and the utmost care employed to 

 prevent any air bubbles from getting into the vessel. After the 

 communication between the renal artery and the flask has been 

 opened, it sometimes happens that blood does not flow until a 

 considerable time has elapsed, owing, apparently, to a tetanic 

 contraction of the vessels in the kidney. 



After the blood has begun to flow it does not do so in an 

 equable stream, as it would do through glass tubes, but its 

 velocity is alternately greater and less, owing to periodic con- 

 tractions of the waUs of the renal vessels, independently of any- 

 nervous influence. If the circulation is arrested for some time 

 and then allowed to go on, the rapidity is much greater after 

 than before the stoppage, but it gradually faUs again to normal 



