130 WHALES 



by no means the easiest of experimental tasks to establish these figures. 

 Nevertheless, as early as 1873, Jolyet carried out such experiments with a 

 Bottlenose Dolphin kept at the Biological Research Institute at Arcachon 

 (France) . The animal was so tame that it did not olDJect to swimming about 

 Avith a bag over its blowhole. The bag was connected by a tube to a spiro- 

 meter, an instrument for determining both the volume and composition 

 of exhaled air. Other investigators have tried to solve the problem in their 

 own ways, but pride of place must be given to the Norwegian physiologist 

 P. F. Scholander, who based his investigations on the work of L. Irving 

 of Swarthmore College (Pennsylvania). Irving had previously investi- 

 gated the respiration of ducks, beavers and muskrats, and Scholander 

 decided to apply the same methods to porpoises and seals. Unfortunately, 

 his experimental subjects proved less tractable than Jolyet's dolphin, and 

 he was forced to tie them up in a tub, and to simulate diving by alter- 

 natively raising and lowering the water level. Despite this handicap, 

 Scholander's investigations proved so fruitful that, in 1938, he was 

 awarded a Rockefeller grant to work under Irving in Swarthmore. Their 

 collaboration has produced many important results, particularly on the 

 respiration of Bottlenose Dolphins and sea-cows. 



It appeared that the estimates of lung capacity calculated from the 

 animals' lung-to-body weight ratio was substantially correct. The lungs 

 of a 70-foot Fin Whale were found to have a maximum capacity of 

 2,000 litres of air, and those of an 18-foot Bottlenose Whale and a young 

 porpoise of 40 and i -4 litres respectively. By comparison, the lung of man 

 has a maximum capacity of 5, and the lung of a horse a maximum capacity 

 of 42 litres. If we refer these figures to body weight, it appears that the 

 lung capacity of Bottlenose Dolphins and porpoises is roughly one-and-a- 

 half times that of terrestrial mammals, while that of Rorquals, Sperm 

 Whales and Bottlenose Whales is only about half that of their relatives 

 on land. Seals and sea-cows were found to have approximately the same 

 lung capacity as terrestrial mammals. 



We have learned why deep divers must take down a minimum of air, 

 while those which stay submerged for long periods but remain close to the 

 surface can take down a large volume of air. In this connexion we might 

 well ask whether, irrespective of their lung capacity, the animals com- 

 pletely fill their lungs before diving. Now, while Grey Seals and sea- 

 elephants are known to make a point of exhaling before they dive. 

 Cetaceans do the reverse and Scholander gained the clear impression 

 that they fill their lungs to capacity. 



That being the case, we might wonder why Rorquals and Sperm Whales 

 with their relatively small lungs do not breathe more frequently than 

 terrestrial mammals and why the respiratory rate of dolphins is so much 



