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XIV. On the Arrangement of the Muscular Fibres in the Ventricles of the Vertebrate 
Heart , with Physiological Remarks. By James Bell Pettigrew, M.l). Edin. ; 
Assistant in the Museum of the Royal College of Surgeons of England ; Extraordinary 
Member and late President of the Royal Medical Society of Edinburgh, &c. &c. 
Communicated by John Goodsir, Esg., F.R.SS. L. and E., Professor of Anatomy in 
the University of Edinburgh. 
Received March 26, — Read April 23, 1863. 
The principal part of the following communication was presented to the Royal Society 
of London, in November 1859, and formed the subject of the Croonian Lecture for 1860. 
An abstract of it was published in the ‘ Proceedings ’ of the Society for April of that 
year. It was subsequently withdrawn for extension and revision, and I have to express 
my regret that the time occupied in this work has, from various unforeseen causes, been 
much longer than I anticipated. 
The paper, as now presented, consists of four parts or sections, — the first section 
being devoted to the anatomy of the ventricle of the fish ; the second to the anatomy of 
the ventricle of the reptile ; the third and fourth treating of the ventricles of the bird 
and mammal. I have adopted this arrangement, because the structure of the ventricle 
in the fish and reptile is to a certain extent rudimentary, and a knowledge of it forms 
an appropriate introduction to the more intricate structure met with in the ventricles 
of the bird and mammal. 
Of the ventricles more particularly examined in the fish, may be enumerated those of 
the salmon, shark, sunfish, fishing frog, turbot, and cod ; in the reptile, those of the frog, 
turtle, tortoise, snake, and alligator ; in the bird, those of the duck, goose, swan, turkey, 
capercailzie, eagle, and emu ; and in the mammal, those of man, the mysticetus, dugong, 
porpoise, seal, armadillo, lion, giraffe, camel, horse, ox, ass, sheep, hog, hedgehog, dog, 
and deer. 
VENTRICLE OF THE FISH. 
In the fish, as is well known, the heart consists of two portions, one auricle and one ven- 
tricle. The shape of the ventricle in the salmon, which has been selected as typical of this 
division of vertebrate animals, is that of a three-sided pyramid, the base of which is per- 
forated by two openings. These openings conduct to a conical-shaped ventricular cavity 
of comparatively small dimensions, the capacity of which is increased by its giving off 
numerous canals, which tunnel the ventricular wall in all directions, particularly towards 
the apex. The walls of the ventricle are accordingly of great thickness, and destitute of 
that solidity which characterizes the walls of the ventricles of the bird and mammal. 
MDCCCLXIV. 3 o 
