IN THE VENTRICLES OE THE VERTEBRATE HEART. 
449 
teristic of the voluntary muscles. Unlike the generality of voluntary muscles, on the 
other hand, the fibres of the ventricles, as a rule, have neither origin nor insertion ; i. e. 
they are continuous alike at the apex of the ventricles and at the base. They are 
further distinguished by the almost total absence of cellular tissue as a connecting 
medium * — the fibres being held together partly by splitting up and running into each 
other, and partly by the minute ramifications of the cardiac vessels and nerves f. 
The manner in which the fibres are attached to each other, while it necessarily 
secures to the ventricles considerable latitude of motion, also furnishes the means 
whereby the fibres composing them may be successfully unravelled ; for it is found that 
by the action of certain reagents, and the application of various kinds of heat, as in 
roasting and boiling $, the fibres may be prepared so as readily to separate from each 
other, in layers of greater or lesser thickness. 
The crowning difference, however, and that which it is the especial object of the 
present paper to treat, is the arrangement of the fibres themselves — an arrangement so 
unusual and perplexing, that it has long been considered as forming a kind of Gordian 
knot in anatomy. Of the complexity of the arrangement I need not speak, further than 
to say that Vesalius, Albinus, Haller §, and De Blainville [| all confessed their 
inability to unravel it. 
Of those who have written more particularly on the structure of the mammalian 
heart, may be mentioned Lower *)[ (1669), Baetholin ** (1678), WiNSLOwff (1711), 
* The little cellular tissue there is, is found more particularly at the base and apex of the ventricles, and is 
so trivial as to be altogether, though wrongly, denied by some. See article “ On the Eibres of the Heart,” by 
Mr. Seakle, in the ‘ Cyclopaedia of Anatomy and Physiology,’ p. 652. 
t When the vessels of the ventricles are injected in the cold state with some material which will stand heat 
(as, for example, a mixture of starch and water), and the heart boiled, the larger trunks from either coronary 
artery are found to give off a series of minute branches which penetrate the ventricular wall in a direction from 
without inwards — these branches, when the dissection is conducted to a certain depth, appearing like so many 
bristles trans fixin g the ventricular wall. As, moreover, the cardiac nerve-trunks accompany the trunks of the 
coronary vessels, while the nerve-filaments cross the smaller branches of the vessels, and the muscular fibres, 
(to both of which they afford a plentiful supply of nerve-twigs,) the influence exerted by the vessels and nerves, 
in muting or binding the muscular fibres to each other, is very considerable. Tide Inaugural Prize Dissertation 
by the author, “ On the Arrangement of the Cardiac Nerves, and their connexion with the Cerebro- spinal and 
Sympathetic Systems in Mammalia,” deposited in the University of Edinburgh Library, March 1861. 
+ Of the various modes recommended for preparing the ventricles prior to dissection, I prefer that of con- 
tinued boiling. The time required for the human heart, and those of the small quadrupeds, as the sheep, hog, 
calf, and deer, may vary from four to six hours ; while for the hearts of the larger quadrupeds, as the horse, ox, 
ass, &e., the boiling should be continued from eight to ten hours; more than this is unnecessary. A good plan 
is to stuff the ventricular cavities loosely with bread crumbs, bran, or some pliant material before boiling, in 
order, if possible, to distend without overstretching the muscular fibres. If this plan be adopted, and the 
ventricles soaked for a fortnight or so in alcohol before being dissected, the fibres will be found to separate with 
great facility. Vaust recommended that the heart should be boiled in a solution of nitre ; but nothing is gained 
by this procedure. 
§ El. Phys. tom. i. p. 351. || Corns de Physiologie, &c. tom. ii. p. 359. 
If Tractatus de Corde, &c. London, 1669. ** Dissert, de Cordis structura et usu. Hafniae, 1678. 
ft “ Sur les Eibres du Cceur et sur ses Valves,” Mem. de l’Acad. Roy. de Paris, 1711. 
