510 NICHOLAS ZOGRAFF. 



very simple and convincing method. For long I took great 

 pains to find a means of injecting one way or the other 

 some fluid into the vessels conducting blood to the labryin- 

 thine apparatus, but unfortunately I did not succeed. But 

 two or three times I thought the fine light blue mass pre- 

 pared according to Beal did penetrate through the gill-arteries 

 from the heart into the apparatus, and that is the reason why 

 in my remarks published in 1886 I ventured to say that Cuvier's 

 hypothesis was very probable. 1 



Operating with chloroform upon Macropodus I observed 

 that both the vessels of the labyrinthine apparatus and the gill- 

 vessels of the fishes thus operated upon were overfilled with 

 blood. Then I tried to rapidly curdle the blood by pouring some 

 boiling water over the organ, and then making it hard with 

 alcohol. My experiment proved to be successful. Not only 

 the labyrinthine apparatus and the gill- vessels, but even the 

 " bulbus arteriosus " were filled with coagulated blood, wherein 

 one could very well distinguish the red corpuscles. After that 

 I began to prepare sections of the part of Macropodus which 

 lies next to the gills and its labyrinthine apparatus, and found 

 that the blood with its red elements could be tinted with 

 boracic carmine so as to enable one to discern the finest blood- 

 vessels. 



Several sections thus prepared convinced me that the artery 

 leading to the labyrinthine apparatus (fig. 7, ar. lb.) is a 

 branch of the artery of the fourth branchial arch (ar. br), and 

 consequently furnishes the apparatus with venous blood, the 

 blood returning from the apparatus to the spinal aorta through 

 the junction which I had already observed before, and through 

 which the injected mass passed into the apparatus. So the 

 labyrinthine apparatus is a supplementary apparatus of the 

 fourth branchial arch, and the circulation of the blood of the 

 gill-apparatus of Labyrinthici differs from the circulation of 

 other Teleostei in the presence of an arterial branch (and 



1 " Ueber den sogenanntess Labyrinthapparat der Labyrintbfische (Laby- 

 rintbici)," von Nicolaus Zograff, ' Biologisches Centralblatt,' Band i, No. 22, 

 1886, p. 687. 



