Modifications of Abel Apparatus. 



79 



steam radiator with "U" tubes of glass set in discs of hard rubber 

 fixed on a central glass rod. All this was enclosed in a water 

 jacket. In spite of our fear that the blood pressure might be 

 insufficient to force the blood through this long course (about 80 

 inches) it works well, and we have carried on an experiment for 

 five hours. The difficulty in preventing leaks where the celloidin 

 tube is tied on the glass we have obviated by first wrapping the 

 joint with rubber adhesive plaster and then tying. The difficulty 

 in tying on the tubes of the inner row when the "U" tubes are 

 ranged round a disc, we have removed by spreading out the "U" 

 tubes flat in a square frame made of rubber and glass which can 

 be turned over when it is necessary to tie the lower row. When 

 the sheaf of tubes is enclosed in a water cylinder plugged at both 

 ends, it is impossible to remedy a leak except by stopping the 

 experiment, but we have simply laid our square frame in an enamel 

 pan of the fluid covered with a glass lid and can reach any part 

 of it at any time without disturbing the circulation. 



Hirudin is very expensive and we have therefore defibrinated 

 the blood of our animals realizing the possible objections to this. 

 Instead of starting with the celloidin tubes full of salt solution 

 they are filled with defibrinated blood of another normal dog and 

 enough of this is kept in a funnel or tank connected with the inlet 

 tube to allow some blood from the machine to run through the 

 outlet tube into the vein while a similar amount is bled from the 

 carotid and defibrinated. This is poured into the funnel and the 

 process repeated till the blood no longer clots when the inlet tube 

 is connected with the carotid canula and circulation proceeds. 

 So rapid is the torrent of blood through such a continuous channel 

 that we have twice connected the inlet and outlet tubes directly 

 with artery and vein without defibrinating and kept up the circula- 

 tion for an hour without the formation of any clot. If the blood 

 pressure sinks, through faulty etherization or other reason the 

 blood clots, as happened in another experiment. 



The most important and difficult part of the problem is the 

 calculation of the proper fluid in which to immerse the apparatus. 

 In our effort to abstract calcium we have tried several and are at 

 present using a fluid calculated to correspond as closely as possible 

 with Abderhalden's published analysis of the inorganic constituents 

 of the dog's blood with the omission of the calcium. 



