1 60 Miscellaneous . 



On the Vascular System of Aiiodonta. By Professor Langer. 



The structure of the circulatory system of the MoUusca having 

 given rise to a great numher of discussions during the last few years, 

 it is interesting to see new data coming in for the solution of the 

 dehate. According to Langer's observations, the vascular system of 

 the Anodontce appears to be closed. The walls of the vessels may 

 be demonstrated in most of the organs. The venous system origi- 

 nates in two ways : in certain parts of the animal (the alimentary 

 canal, tentacles, and sexual glands) it is the simple continuation of a 

 superficial capillary network ; in other organs (the foot and mantle) 

 it arises from a peculiar tissue {pchivellgewehe) capable of dilatation. 



The venous blood of the body flows into the median venous sinus 

 discovered by Bojanus, and passing thence through the meshes of the 

 organ which that anatomist regarded as a lung*, arrives in the 

 branchiae. The venous blood of the central parts of the mantle, on 

 the contrary, does not pass into the respiratory organs, but arrives 

 directly in the auricle of the heart, like the venous blood of the walls 

 of the vestibule of the corpus Bojani and that of the partitions of the 

 branchial walls. The arterial circulation, consequently, is not com- 

 pletely isolated from the venous. The afflux of the blood into the 

 branchiae takes place across the vessels of the corpus Bojani, which 

 constitutes a sort of rete mirabilis between the median venous sinus 

 and the branchial arteries. 



Langer was unable to ascertain the presence of an aquiferous system 

 in the Anodontcn. He nevertheless convinced himself of the exist- 

 ence of a direct communication between the vascular system and the 

 exterior. It is the corpus Bojani that serves for the absorption of 

 water. The aperture which was described even by Bojanus under 

 the name of respiratory orifice, leads into the space which Keber has 

 called the vestibule, and which is itself in direct communication with 

 the proper cavity of the corpus Bojani. These two cavities are only 

 enlargements of a long viscus twisted in different directions, and of 

 which the extremity opposite to the orifice of the organ of Bojanus 

 is nothing but the well-known aperture of communication of the 

 pericardium. The water is thus conducted into the pericardium. 

 The two orifices which Keber has described in the latter at the side 

 of the rectum are constant ; they lead into the venous network of 

 the mantle. 



Analogous observations have been made by Gegenbaur in the 

 Heteropoda, by Agassiz in the Lamellibranchiata, Sac. Langer sup- 

 poses that the introduction of water from without into the sangui- 

 ferous system is for the purpose of furnishing calcareous salts required 

 for the formation of the shell. We must confess that we do not 

 know why the carbonate of lime should be furnished in this way 

 rather than any other. — Sitzungsber. der Akad. zu Wien, 1856, 

 p. 150. Abstract in Bibl. Univ. de Geneve j Nov. 1856, p. 252. 



* This organ, known under the name of corpus Bojani, is generally 

 considered as the kidney. It is to be noted, however, that Schlossberger, 

 in some recent investigations, was unable to discover in it the least trace of 

 uric acid. 



