Coordination of the Auricles and Ventricles. 79 



Villafranca. Ligatures were applied between auricles and ven- 

 tricle and the pulsations counted before and after. The histolog- 

 ical examination of stained serial sections was made later in the 

 Physiological Institute of Bern. 



An abbreviated protocol will illustrate the experimental results. 



October 4, 1907. The beating heart of a large lizard whose 

 brain was destroyed, was turned over within the open thorax so 

 that the dorsal surface, where the chief nervous connections 

 between auricles and ventricle are to be found, was lying upward. 

 Whitish cords connect the auricles with the ventricle ; the left cord 

 is finer than the right and not always distinguishable. Besides 

 these cords only connective tissue can be noticed between auricles 

 and ventricle. 



The heart was beating 25 times a minute, auricles and 

 ventricle beating in regular sequence. After ligating the right 

 cord the ventricle stopped beating for one minute, while the 

 auricles continued to beat irregularly. Four minutes later the 

 auricles were beating 18 times and the ventricle 10 times a minute. 

 Later counts gave the following relations: 24 to 12, 24 to 18, 

 22 to 16. Twenty minutes after ligature the auricles were beating 

 25 times and the ventricle 22 times a minute. After ligating the 

 left cord also, auricles and ventricle stood still for about one 

 minute, when both began to beat. Again the relations were 10 to 

 3, 10 to 5, and 14 to 6. 



Other experiments gave constantly similar results. 



Kronecker and Spalitta observed in Palermo similar incoordi- 

 nation after applying ligatures to the heart of a sea turtle, but the 

 results were not constant. (Report of the Berlin Academy of 

 Science, May 25, 1905.) 



In the hearts of lizards in which the cords were not visible, 

 ligatures made through the corresponding part of the wall pro- 

 duced the same incoordination. Ligatures on the anterior (ven- 

 tral) surface had no effect. 



The histological examination showed that there are no traces 

 of muscle bridges connecting the auricles with the ventricle. 

 Neither is there in the septum a tract of muscles corresponding 

 to the bundle of His. There are, however, a multitude of nervous 

 connections between auricles and ventricle. The cord consists 



