433 



April 19, 1860. 

 Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 



Professor Auguste De la Rive, of Geneva, and Sir John Bowring, 

 were admitted into the Society. 



The CROONIAN LECTURE was then delivered by JAMES PETTI- 

 GREW, Esq., " On the Arrangement of the Muscular Fibres of the 

 Ventricular portion of the Heart of the Mammal." 



(Abstract.) 



The Lecturer began by referring to the descriptions of the arrange- 

 ment of the ventricular fibres of the heart given by previous in- 

 quirers, more especially Lower, Senac, Wolff, Gerdy, Duncan, and 

 Reid ; he then proceeded to give an account of the results of his 

 own investigations, which had been conducted on the hearts of the 

 Sheep, Calf, Deer, Ox, Horse, &c. ; all of which, he observed, bear a 

 perfect resemblance to the human heart* . In order, as much as pos- 

 sible, to overcome the difficulties of the subject, he availed himself of 

 drawings, explanatory diagrams, and models illustrating the course 

 and relation of the fibres. To these last, however, he observed he 

 attached no special importance, further than that they were useful 

 vehicles of communication ; and it was to the dissections themselves, 

 some of which were before the Society, that he looked for a corro- 

 boration of the statements he advanced. 



Commencing with the left ventricle, which he believes to be the 

 typical one, the Lecturer stated that, by exercising a little care, he 

 had been enabled to unwind as it were its muscular substance, and 

 so to separate its walls into several layers f, each of which is charac- 

 terized by a difference in direction. Seven layers, at least, can be 

 readily shown by dissection ; but he believes they are in reality 

 nine ; viz. four external, the fifth or central, and four internal. He 

 explained how the external fibres are continuous with the internal 

 fibres at the apex, as was known to Lower J, Gerdy , and others, 



* Mr. Pettigrew's researches include also the arrangement of the fibres in the 

 ventricles of the Bird, Reptile, and Fish. 



f Senac (Traite de la Structure du Coeur, &c. [Paris, 1749] , planche 8) figures 

 four layers ; and Searle (Cyc. of Anat. and Phys., art. " Heart") speaks of three. 



t Tractatus de Corde, &c. London, 1669. 



Recherches, Discussions et Propositions d'Anatomie, Physiologie, &c. Paris, 

 1823. 



2 H2 



