Miscellaneous, 225 



On the Structure of the Heart In Fishes of the Genus Gadus. 



By M. JOURDAIN. 



In 1858 Professor Hyrtl of Vienna published an interesting 

 memoir on the absence of blood-vessels in the hearts of certain 

 Vertebrata. He announced that the heart in the Batrachia is com- 

 pletely deprived of vessels — a peculiarity previously unknown, and 

 the reality of which, we may say in passing, we have ascertained in 

 the Batrachia of this country. The aortic bulb alone possesses some 

 very delicate vascular branches, comparable to the vasa vasorum^ of 

 which M. Hyrtl indicated the origin, course, and termination with 

 the rigorous exactitude characteristic of that anatomist, a recognzied 

 master in the art of injection. 



The heart in the bony fishes presents a state intermediate between 

 the heart without vessels of the Batrachia and the vascular heart of 

 the Mammalia and Birds, — that is to say, that only one-half of the 

 thickness of the ventricular wall, the outer stratum, receives branches 

 of the arterial system, and that the other half is completely deprived 

 of them. The heart in the osseous fishes might therefore be desig- 

 nated a semivascular heart. The central organ of the circulation 

 presents this plan of construction in the fishes of our coasts. The 

 most penetrating fine injections never implicate more than the outer 

 layer of the ventricle, the compact structure of which approaches 

 what we are accustomed to see in the heart of the Mammalia and 

 Birds. The inner layer, in which, we repeat, the most minute ex- 

 amination fails to detect the least trace of vascularity, presents, on 

 the contrary, a soft and spongy texture, and separates readily from 

 the outer layer of dense tissue — a peculiarity alluded to by Cuvier, 

 Dollinger, and Rathke, who did not, however, understand its 

 significance. 



The Gadi present an exception which the mode of circulation & 

 fishes renders worthy of remark. Like that of the Batrachia, the 

 heart of the Gadi is destitute of the vascular element. Fine injec- 

 tions driven in through the arteries so as to return by the veins, never 

 penetrate into the walls of the ventricle, nor into those of the auricle. 

 The aortic bulb alone possesses some very slender branches ; but 

 these never pass the scissure which separates this last cardiac 

 chamber from the preceding one. The arterioles are furnished by 

 the hyoidian artery, which is dependent upon the first two epi- 

 branchials ; the venules open into the hyoidian veins, which in their 

 turn are tributaries of the common venous sinus. With this absence 

 of vessels corresponds a peculiar structure of the ventricular walls, 

 very analogous to that observed in the Batrachia. The muscular 

 fibres, instead of constituting by their apposition a dense and compact 

 tissue, form bundles and trabeculflp, which divide and interlace in 

 such a manner as to give origin to an areolar and spongy mass. It 

 is in the irregular passages and lacunar spaces thus produced that the 

 venous blood diffuses itself at the moment of the ventricular diastole. 

 At this moment the blood permeates the walls of the ventricle hke 

 a sponge, and it is pressed out again by the movement of systole 

 which succeeds. 



^7171. ^ Mag, N. Hist, Ser. 3. Vol, xix. ] 6 



