345 



The Refractive Indices of the Eye Media of some Australian 

 Animals. 

 By Judah Leon Jona, D.Sc, M.B., B.S. 



(Communicated by Prof. J. N. Langley, F.R.S. Received August 23, — 

 Read November 16, 1911.) 



(From the Physiological Department of the University of Melbourne.) 



While carrying out an investigation on the osmotic pressure of the blood 

 and body fluids of various Australian animals I was desirous of supple- 

 menting the data thus acquired with estimations of other physical characters. 

 The refractive indices of the eye fluids presented some interesting features, 

 and I give here in tabular form the results obtained. 



The instrument employed was the Abbe refractometer. The outer layers 

 of the crystalline lens were sufficiently fluid to be spread out as a refracting 

 layer on the prism. 





IX of 

 aqueous 

 humour. 



vitreous 

 humour. 



lens (outer 

 layers). 



Temp., 



Land Mammals — 













Babbit 





1 -336 





1-43 



10 -3 







1 -336 



1 -338 





16 -5 



(B) 





1 337 







15 -5 



Land Reptile — 

















1 -3357 



1 -3362 





15—16 



Amphibia — 













Syla aurea 





1 -3355 





1 -4675 



11 -7 



Fish— 













Teleost3 — 













Marine — 













Barracouta {Thy r sites ati 



«) (A) 



1 -3353 



1 -3354 



1 -433 



12 



(B) 



1 -3353 



1 -3354 





12 



Fresh Water — 













Murray Cod ( Oligorus 



Mac- 











quariensis) (A) 





1 -3361 













1 -3362 





1-43 



12 







1 -3524 



1 -3772 



1-46 





Tap Water- 

























Sea Water— 

















1 -3404 









In connection with these results it is of interest to note that right 

 through the Vertebrates from Mammals down to Teleostean fishes, marine 

 and fresh water, the refractive indices of the aqueous humour, vitreous and 

 lens (outer layers) were about the same in each class of animal, being 



