PERFUSION OF VESSELS. LYMPH-HEARTS 



101 



afterwards for that containing the drug, and a third determination 

 made in the same way (average of three counts). 



The same method is used for perfusion of the organs of mammals. 

 The cannula is tied into the artery of the (excised) .organ, which is 

 placed in a jacketed funnel warmed to 38 C. : the perfused fluid, 

 which must also be warmed before entering the organ, escapes by the 

 vein and runs down the funnel into a measuring vessel. In this way 

 perfusion can be conducted through the kidney of the dog or sheep, or 

 through the vessels of a limb. In 

 mammals it is usual to allow oxy- 

 gen to bubble through the Ringer 

 solution used for perfusion and to 

 add gum arabic to the Ringer to 

 prevent oedema (Bayliss). It is also 

 advantageous to render the pressure 

 variable by intermittingly checking 

 the inflow, thus imitating the arterial 

 pulse. 



Methods of recording the outflow 

 of fluid. 1. The sequence of drops of 

 any fluid can be recorded by aid of an 

 electric drop recorder connected with 

 an electro-magnetic signal, which 

 writes upon the smoked paper of a 

 drum. 



2. Another method of graphically 

 registering the rate of flow, especially 

 if the drops follow one another too 

 fast to be recorded individually by a 

 drop-recorder, is furnished by the 

 "tilter" shown diagrammatically in 

 Fig. 80. This is a small vulcanite or 



celluloid trough with open ends, with a septum across the middle \ the 

 trough is balanced on a vulcanite knife-edge. The drops are led over 

 the middle, and, falling on the side of the septum which happens to be 

 uppermost, they gradually fill that side of the trough. When full, it 

 overbalances, and the trough tilts over to the other side, when the 

 process is repeated. Each movement of the tilter is registered, 

 either by an electrical or a pneumatic arrangement, upon the recording 

 paper, on which the time is also written. The capacity of the tilter 

 being known, the amount of fluid flowing in a given time is ascer- 

 tained. The record will continue automatically for long periods. 



3. A third method is to allow the fluid to flow into a vessel of 



FIG. 80. Diagram of tilter. The 

 rocking movements are recorded 

 either by allowing the accumu- 

 lated fluid to actuate a tambour, 

 or by an electro-magnetic signal. 



