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BRUNER. [Vol. XVI. 



the shifting of the attachment of the sinus-atrium valve — is to 

 be accounted for by the disappearance of the septum atriorum. 

 The valve itself shows no sign of degeneration, which indeed 

 could not be expected to occur here, for the condition which 

 requires the presence of a valve at the sinus-atrium opening is 

 certainly not affected by the loss of lungs. 



It is worthy of note that the loss of lungs has affected the 

 pulmonary artery and the pulmonary vein in an altogether 

 different way. As already stated, the survival of the artery 

 in lungless salamanders has been reported by Hopkins (14), 

 Bethge (i), and Miss Woldt (33). I have observed the artery 

 also in Salamandrina, where, however, it receives its blood only 

 through the ductus Botalli, the proximal portion of the vessel 

 having disappeared. In all of the forms studied, the pulmo- 

 nary artery supplies certain parts (oesophagus, skin), to which it 

 is distributed also in salamanders with lungs. Such an acces- 

 sory saving function the pulmonary vein of lungless salaman- 

 ders did not possess. 



The fact that the septum atriorum disappears with the lungs 

 indicates clearly that in salamanders with lungs the septum 

 performs a function which becomes superfluous or impossible 

 after the loss of those organs. This function is the separation 

 of the venous blood of the right auricle from the aerated blood 

 of the left auricle. But what is the significance of this separa- 

 tion if the two sorts of blood are afterward mixed during their 

 passage through the ventricle and conus } Or is there, after 

 all, in salamanders with lungs, a partial separation of aerated 

 and venous blood in its entire course through the heart .-• 

 Such a separation occurs, as is well known, in the heart of 

 Rana. Now as regards the atrium and ventricle we find essen- 

 tially the same structure in Salamandra as in Rana. It is true 

 that the septum atriorum of the salamander is perforated, while 

 that of the frog is not. But during the brief stay of the blood 

 in the auricles the small perforations which have been described 

 in Salamandra would permit little mixing of the blood. There 

 would be a much better opportunity for this to occur in the 

 ventricle ; but here we have the same spongy condition in Sala- 

 mandra and Rana. So far, then, Rana does not seem to have 



