772 



lie vagi have the same iiifliieiu'e on Ihe Hction currents of the dia- 

 [>hragin, as found in the cat, this influence in the rabbit being even 

 much more distinct than in the cat. 



Anaesthesia of the animal by subcutaneous injection of urethane (ca. 1 gr. pro 

 KG. of body-weight). By means of artificial heating we tried to keep the body 

 temperature of the animal as constant as possible. Incision of the abdominal wall 

 in the linea alba, of about 3 cm., beginning tiirectly caiidally of the ensiform 

 cartilage. This processus was kept in upright position by fixing it with a forceps 

 to a support, which was isolated electrically from the table on which the animal 

 was lying. Then we isolated as carefully as possible one of the anterior slips 

 of the diaphragm and put a small piece of celluloid under it, so as to insulate 

 this part of the muscle as well as we could from the other parts of the diaphragm 

 and its surroundings. In this slip were hooked two very small hook.s at a distance 

 from each other of about 1 — 1,5 cm, which served as electrodes, through which 

 the action currents of the muscle were lead off to the string galvanometer (large 

 pattern of Edelmann). In our earlier experiments these hooks were of copper and 

 therefore polarisable electrodes, in our later experiments we made use of similar 

 shaped silver hooks, galvanoplastically coated with a layer of silver chloride; these 

 electrodes were non-polarisable. As was to be expected we could not find that the 

 use of these different electrodes gave rise to any appreciable difference in our 

 curres, because it cannot be expected that the polarization of the copper hooks 

 has a distinct influence on the weak, frequent and alternating action currents of 

 the muscle. The hooks were connected with very Ihin copper wires to the thicker 

 wires leading to the galvanometer, so that the movements of the muscle could be 

 followed quite freely by the elect: odes and connecting wires. By closing the opening 

 in the abdominal wall with a pad of dry cottonwool loss of heat of the muscle 

 and other disturbing influences were prevented. 



The respiratory movements of the diaphragm were reproduced on a kymograph 

 with blackened paper and underneath these tracings we marked electromagnelically 

 during which part of the pneumogram the action currents were registered. The 

 table with the animal wap carefully insulated by putting it on large blocks of 

 paraffine. 



After these preliminaries we fust luuk the action currents of the diaphragm 

 during normal inspiration, i.e. before the elimination of the vagi. Then both these 

 nerves were carehilly prepared at the neck and eliminated without excitation, 

 either through local anaesthesia with ether vapour or through local application 

 on the nerves of a 1 "/(, solution of novocain. When Ihe elimination of the vagi 

 established itself by a change of the respiratory movements of the animal, we 

 again registered the action currents of the insulated anterior slip of Ihe diaphragm. 

 We might draw attention to the fact thai by a special devise it was possible to 

 take our electrophysiological records in every desired phase of the respiratory 

 contraction of the muscle. 



In ail our experiments in wliicth the elimination of both vagi is 

 followed by a distinct change of the mechaiucal type of respiration, 

 we could establish the fact that the elimination of the nervous 

 impulses (jices rise to <i di.siinci augmentation of the frequency of the 



