814 REPORT— 1897. 



the auricle), or with a glass tube inserted through the carotid artery into the left 

 ventricle. In the latter case, a valve in the course of the connecting tube prevents 

 any back-flow of blood. Both femoral arteries (or sometimes both brachials) are 

 exposed. A cannula (collecting cannula) is inserted into a branch of one of the 

 arteries and the other is laid on two hook-shaped platinum electrodes connected 

 with the Wheatstone's bridge, with which a telephone is connected in the usual way. 

 Weak induction shocks from the secondary of a du Bois coil are sent through the 

 arrangement, including the piece of artery on the electrodes, and tlie bridge is 

 balanced. When the mixture of blood and salt solution reaches the electrodes the 

 balance is upset, and the telephone announces the moment of arrival of the mixture. 

 A sample of blood is now drawn off by means of the collecting cannula, during 

 the passage of the salt solution, and immediately defibrinated. Then it can be 

 determined at leisure how much of the salt solution must be added to a sample 

 collected before the injection to make its resistance equal to that of the sample 

 collected during the passage of the mixture. Numerous observations can be made 

 in this way on one animal ; and from these data the output of the heart for the 

 period of injection, and, therefore, the pulse-rate being known, for a single beat, can 

 be calculated. 



Specimens of Mestdts. — In a dog weighing 32-26 kilo, the average output (for 

 the first si.x observations) was 568 c.c. per beat, equal to 2'71 c.c. per kilo, of body- 

 weight per second, with an average pulse-rate of 1*54 per second. In a dog of 

 body-weight 6-48 kilo., the average output was 14'8 c.c. per beat, or 3'52 c.c. per 

 kilo, per second for an average pulse-rate of 1-61. In an animal of intermediate 

 size (18"2 kilo.) the average output for the first five observatians was 41'6 c.c. per 

 beat, or 2-ul c.c. per kilo, per second for an average pulse-rate of 1"01. 



In general it may be said that the results of these experiments go to show that 

 the more recent measurements of Tigerstedt and Stolnikow are too low, while the 

 older numbers of Volkmann and Vierordt are too high. 



The animals were all completely antesthetised with morphia and ether, or ACE 

 mixture, and were killed before recovering from the anaesthetic. 



[Published in full in Journ. of Physiology, 1897, v. xxii., p. 159]. 



2. Observations on the Mammalian Heart. By W. T. Porter. 

 Experimental evidence was offered in support of the following propositions : — 



A. On the cause of the heart-beat. 



1. The cause of the rhythmic contraction of the ventricle lies within the 

 ventricle itself. 



2. The cause of the rhythmic contraction is not a single, localised co-ordination 

 centre ; the co-ordination mechanism, whatever it may be, is present in all parts 

 of the ventricle. 



3. The integrity of the whole ventricle is not essential to the co-ordinated 

 contraction of a part of the ventricle. 



4. The apex of the mammalian heart possesses spontaneous rhythmic contrac- 

 tility, 



5. Assuming that the general belief in the absence of nerve-cells fi-om the 

 apical part of the ventricle is correct, these experiments demonstrate that nerve- 

 cells are not essential to spontaneous, long-continued, co-ordinated contractions of 

 the ventricle. 



B. Fibrillary contractions do not destroy beyond recall the power of normal 

 rhythmic, co-ordinated contraction of the heart muscle. 



C. The influence of ventricular systole on the blood'Jlow through tJte heart 

 muscle. 



1. The contraction of the heart compresses the blood-vessels in the substance 

 of the heart. 



2. The systole aids the circulation of the blood through the heart muscle. 



