461. REPORT — 1891. 



The Structure and Function of the Mammalian Heart. — Report of 

 the Committee^ consisting of Professor E. A. Schafer (Chairman), 

 Mr. A. F. Stanley Kent (Secretanj), and Professor C. S. SHER- 

 RINGTON. (Drawn up by the Secretary.) 



The research may be divided into three parts : — 



1. Observations on the Structure of the Heart. 



2. Experiments on the Relation between Structure and Function. 



3. Experiments with Anaesthetics. 



1. Observations on the Structure of the Heart. — These observations 

 have been made principally on human hearts, and tend to show that the 

 condition which I have described' in the hearts of animals lower in the scale 

 persists even in man. That is to say, the auricles and ventricles are 

 connected by strands of muscular tissue passing across the groove, though, 

 as might be expected from my former observations, these strands are less 

 marked in man than in the lower animals. 



In man, as in all other animals examined, the muscular connection is 

 more perfect in the young condition, and the younger the subject the more 

 perfect the connection. 



To go more into detail, the ring at the base of the auriculo-ventricular 

 valves is composed of a dense mass of white fibrous tissue in which are 

 scattered many connective-tissue corpuscles, and this mass becomes continu- 

 ous with the connective tissue running between the muscular fibres of 

 auricle and ventricle respectively. 



The greatest development of connective tissue takes place at the bases 

 of the valves, which are supported on specially thickened portions of the 

 ring, and are largely composed of bundles of fibres running out from it. 



Bundles of muscular tissue also occur in the valves, and these bundles 

 are usually connected directly with the muscle forming the walls of the 

 auricle. In actual shape and arrangement the fibrous tissue forming the 

 ring differs in different situations. 



At the posterior aspect of the left ventricle the auricular muscle is 

 completely separated from that of the ventricle by a more or less pyramidal 

 mass of connective tissue, the base of the pyramid being directed outwards 

 and forming part of the external surface of the heart, the apex being 

 directed inwards and becoming continuous with the base of the mitral 

 valve, The auricular muscle runs downwards on the inner aspect of this 

 mass of fibrous tissue, and ends as a thin sheet just above the base of the 

 valve. The ventricular muscle ends as a much thicker mass just beneath 

 the base of the valve. 



An exhaustive examination has been made of the relations of muscle 

 and connective tissue in this situation, but a description without figures 

 would be tedious, and followed only with difficulty. Suffice it to say that 

 in the human heart, as in the hearts of other animals, the auricles and 

 ventricles are connected by muscular tissue, and their connection is the 

 more perfect the younger the heart. 



2 and 3. Experiments on the Relation of Structure to Function and 



' Journal of rhyslology, XIY., 1 and 5. 



