346 H. C. VAN DER HEYDE 



than A. And now when the animal comes to the surface it 

 expires! After that it dives again! It is obvious that in this 

 system of reasoning there must be a mistake. In the beginning 

 I tried to find its solution in the process under water and tried 

 to solve the following question: Is the diffusion of oxygen into 

 the bubble sufficient to cover this loss? 



This means : 'Has this oxygen diffusion a biological importance? 

 This has been denied by Ege in his paper cited above. My 

 first hypothesis was that perhaps this author had made a mistake 

 in his complicated calculations or in the determination of the 

 different data used in these calculations. I'^ therefore took up the 

 problem in my own way, but my results are the same as those 

 of Ege. 



a. Bohr has given a formula (used also by Ege) which enables 

 us to find out the quantity of gas which diffuses into or out of 

 a bubble in a certain time. The modification which Ege used is 



Pj _ P2 = — '- , in which pi — p2 is the difference in pressure 



7. S 



between bubble and water (Ap), M the change in volume (Av), 

 7 the diffusion coefficient of the gas and S the surface through 

 which diffusion takes place. 



What I wanted to see was whether O2 would diffuse in faster 

 than No diffuses out or not. Now, when we suppose that one 



diffuses as fast as the other, we have : ( — ) = — ( — ) • 



\Ar/o, Vat/n, 



Substituting Bohr's formula, we have: 



S. 7o,. Apo, ^ _ S. 7n,. APn, 



760 760 



Substituting y^, = 0.029 and 7n. = 0.009 (Ege), we get: 



^Poo- = — 0.31 Ap^,. In the water p^, is 601 mm. Hg, 



pressure O2 is 159 mm. Hg. When we take, for instance, the 



analytical result of our table 1, analysis 3, as standard for the 



composition of the air after the animal has moved for some time 



in the water, Apo^ appears to be — 136 mm. Hg. To balance 



1* I am very much obliged to my friend the physical chemist, Prof. Dr. Allen 

 E. Stearn, who helped me in working this problem and had the kindness to look 

 over these pages. 



