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XLVI. — On the Relations, Structure, and Function^ of the Valves of the Vascular 

 Si/stem in Vertehrata. By James Bell Pettigrew, M.D. Edin., Assistant 

 in the Museum of the Royal College of Surgeons of England. Communicated 

 by William Turner, M.B. (Plates XXVIII., XXIX.) 



(Read 21st March 1864.) 



Introductory Bemarks. 



The rapid advances made of late in the diagnosis of cardiac and other diseases 

 affecting the organs of circulation, render the present inquiry into the normal or 

 healthy condition of the valves of the vascular system, not more important 

 anatomically, than medically. As the nature and composition of the parts in 

 which valves are found in some instances materially influence their action, I 

 have deemed it necessary to advert briefly to the properties and structure of the 

 veins and arteries, vv^hen describing the venous and arterial or semilunar valves ; 

 and to the arrangement of the muscular fibres in the ventricles, when point- 

 ing out the peculiarities of the auriculo-ventricular ones. As, moreover, much 

 information is to be obtained by comparing analogous structures, I have, in 

 the present instance, not confined my observations to any particular form 

 of valve, but have examined in succession the entire valvular arrangements 

 of the fish, the reptile, the bird, and the mammal ; my object being to arrive, if 

 possible, at a correct knowledge of the more elaborate varieties as they exist in 

 man, and in the higher mammalia. 



In order to simplify the numerous relations and complicated structure of the 

 several valves met with, as well as to obviate the necessity for entering largely 

 into anatomical details, the present paper has been fully illustrated by photo- 

 graphs and drawings from dissections, and from casts representing the valves in 

 action. The photographs, thirty-four in number, were taken for the most part 

 from the specimens while in the fresh or recent state, by Mr Ayling and myself. 

 Of the drawings, twenty-three in number, that marked 33, Plate XXVIII. and 

 the last six of Plate XXIX., are by my friend Dr Henry Season Wilson. The 

 remaining fourteen are by myself. For permission to examine and figure several 

 of the specimens illustrating the peculiarities of the valvular arrangements of the 

 fish and reptile, I am indebted to the kindness of the Council of the Royal College 

 of Surgeons of England. The dissections and casts, which are numerous, Avere 

 made with a special view to this inquiry, and are preserved in the Museum of the 

 Royal College of Surgeons of England, where they may be consulted. 



VOL. XXIII. PART III. 9 s 



