LABYRINTHINE APPARATUS OF LABYRINTHIC FISHES. 509 



functions of any organ would be possible either after exact or 

 precise physiological experiments, or after having functionally 

 studied the anatomy of the organ by comparing its structure 

 with the structure of already well-known organs, the physio- 

 logical functions of which are indisputable. The first method 

 we cannot adopt. Notwithstanding my trying to introduce 

 a very fine bent glass tube under the gill-operculum into the 

 cavity of its labyrinthine pouch, it seemed impossible to do so 

 without making ruptures through which little bladders of gas 

 do not enter in the pipe but pass out. Perhaps if I had 

 examined a greater amount of living material I could have 

 accumulated and analysed a certain quantity of gas from the 

 labyrinthine pouch, but the material I had was insufficient, 

 and therefore I could not solve the question by mere experi- 

 menting. I then applied myself to the study of facts got by 

 anatomy: Could the capillary net that has itsrarteries and 

 veins be an brgan for oxygenising blood? Did it let in venous 

 blood 1 and let out arterial, or vice versa ? To solve the ques- 

 tion I applied injections. Injections through the: arteria bran- 

 chialis, which is very fine and slender, gave no results ; injec- 

 tions through the spinal aorta almost the same ; I say " almost,' 

 because once after having made some unsuccessful injections 

 I happened to inject some of the fluid through the aorta into 

 the labyrinthine apparatus, and into a part of the branchial 

 arches in a direction opposite to the course of the blood. But 

 this not quite successful experiment, together with the results 

 obtained on another occasion, convinced me that the labyrin- 

 thine apparatus is in reality a supplementary respiratory appa^ 

 ratus, helping the fish to breathe while in the open air. < or in 

 the damp atmosphere of drying water-basins. The causes of 

 my supposition are as follows V — Cuvier had made a supposition 

 that the vessels of the labyrinthine apparatus are supplied with 

 blood from the gilli-artery which' passes through a separate 

 branch. But for all the preeiseness of Cuvier's experiments 

 this great naturalist did not succeed in seeing the supposed 

 connection, and had to- limit himself to supposition.: > All 

 my efforts seemed to fail till I happened to fall' upon a 



