340 



H. C. VAN DER HEYDE 



After the animal has dived we can observe the following move- 

 ments of the droplet: 



Animal opens cleft. 



Alo Yemenis up and down, 



under water. 



Fig. 2 Schematic representation of the movements of the droplet 



D. In the first place, a regular retrogression of the droplet at 

 a slower rate, but over a greater distance than was covered during 

 the expiration. When the animal stays under water for a long 

 time, the droplet scarcely shows any more movements. 



