RESPIRATION IN SOUTHERN WHALES 369 



exhaustion observed on the first appearance of a wounded whale at the surface after a 

 descent of 700 or 800 fathoms perpendicular does not depend on the nature of the 

 wound it has received, . . . but is the effect of the almost incredible pressure to which the 

 animal must have been subjected." 



Roy Chapman Andrews (19 16) records being told that a Blue whale dived straight 

 down, taking one-quarter of a mile of rope (220 fathoms), and remained below 32 min. 

 A Southern Blue whale sometimes takes out 300 fathoms of rope in a steep or nearly 

 vertical dive. 



So much for diving under stimulus. Very little is known about the depth to which 

 whales normally dive. Racovitza (1903) estimated 100 m. as the normal maximum. 

 It has been found in the course of plankton investigations in Antarctic waters that 

 whales' food, Eiiphausia superba, occurs anywhere between the surface and 200 m. or so, 

 and that large swarms, such as would concern the whale more than stray individuals, 

 are found either at the surface or anywhere between the surface and 100 m. This sug- 

 gests that the lower limit of a Blue whale's normal activities in the vertical plane may 

 be 100 m. 



A case was related to me in 1931 of a dead Sperm whale which was found off the 

 Peruvian coast entangled in a submarine cable which had broken at a depth of 500 

 fathoms. The mate of the cable ship 'AH America' informed me that when the cable 

 was hauled to the surface it was caught in the angle of the whale's jaws and a loop was 

 twisted round the tail. From these observations it is probable that the whale became 

 entangled in the cable while actively engaged, possibly in pursuit of a cephalopod. The 

 evidence available thus goes to show that whales of various species are able to sustain 

 hydrostatic pressure up to 10 atmospheres in normal life and even greater pressures 

 under provocation. It should, however, be borne in mind that Sperm and Right whales 

 may differ widely in their diving capabilities from Balaenopterids. 



Breath retention. It will be appropriate at this point to consider what may be 

 expected to be the effects of the whale's habit of life on the respiratory system. In the 

 first place a whale must hold its breath. Instead of enjoying a continuous ventilation 

 of the lungs, as do land mammals, the whale has to depend on an intermittent filling and 

 emptying of the lungs which occurs once in 10 or 15 min. (A land mammal, of which in 

 this paper man has been taken as an example, is quite unable to hold the breath for 

 more than i min., though longer periods may be endured after training [Starling].) The 

 natural consequences of this compulsory holding of the breath are a tendency to 

 shortage of oxygen and accumulation of carbon dioxide. 



It may reasonably be expected that a whale will return to the surface to breathe when 

 actuated to do so by some mechanism analogous to the respiratory centre in man. The 

 system of ventilation in human beings does not provide for a complete change of air at 

 every breath. Only a part of the air in the alveoli, or ultimate subdivisions of the bron- 

 chioles, is changed at each breath, so that continuous breathing is necessary. The whale, 

 on the other hand, takes only one breath and disappears below the surface again. It 

 would thus be to the whale's advantage to effect as complete a change of air in the lungs 



