of body weight, but we also recognize 

 that the data available to us represent 

 only a small portion of the full curves. 

 Tidal volume increased about 8 fold 

 as body weight tripled: the correspond- 

 ing value for minute ventilation was 

 10 or 12 fold. Comparison of this 

 growth rate with that of terrestrial 

 mammals is awkward, because of 

 marked changes in their respiratory 

 rate during growth (Watson and Low- 

 rey. 1962). while respiratory rate in 

 the whale was constant. In terrestrial 

 mammals, tidal volume changes as a 

 function of lung volume (which in 

 turn varies as a cubic function of 

 length), while minute ventilation 

 changes as a function of metabolic 

 rate (Tenney and Kemmers. 1963); 

 a more complex function of growth, 

 which is not linear on any conve- 

 nient parameter of body size because 

 of growth spurts during early and 

 late childhood (Benedict and Talbot. 

 1921). 



The increase in the metabolic rate 

 of Gigi II corresponded to the in- 

 crease in her ventilation, and for a 

 tripling of weight, increased about 10 

 fold. This increase is of the same order 

 as the increase in human metabolic 

 rate during the first year (about 8 

 fold) (Benedict and Talbot. 1921). 

 and is consistent with our general 

 impression that growth in the whale, 

 whether of body weight, lung volume, 

 or metabolic rate, proceeded in paral- 

 lel with, or only slightly more rapidly 

 than, human growth. 



Observation of animals at the ex- 

 tremes of body size invites inter- 

 species comparisons of biological 

 phenomena. The existing data for two 

 such correlations; of lung volume 

 with body size (Tenne\ and Remmers. 

 1963), and of metabolic rate with 

 body size (Kleiber. 1961), are par- 

 ticularly well organized. Tenney has 

 shown that lung volume is closely 

 related to body mass (over a range 

 of body mass of 5 orders of magni- 

 tude) by the equation: log lung vol = 

 1.02 log body weight — 1.25, with 

 volume in liters and weight in kg. 

 This yields a predicted lung volume 



in Gigi II of 410 liters at 6,150 kg, 

 which corresponds closely to our 

 measurement of 428 liters, but which 

 diverges widely from values obtained 

 early in her growth. Tenney measured 

 total lung capacity (TLC) of excised 

 lungs, and we measured resting lung 

 volume: this ordinarily considerable 

 difference is fortuitously minimized 

 by the fact that resting lung volume 

 in the whale is a larger fraction of 

 TLC than is the case for terrestrial 

 mammals. This measurement permits 

 considerable extension of Tenney's 

 data, for his largest animal, also a 

 cetacean, weighed only 1,750 kg. 



Kleiber studied the metabolic rates 

 of animals also differing in body size 

 by about 5 orders of magnitude, and 

 concluded that metabolic rate was 

 best related to the 0.75 power of 

 weight, by the equation: log A/ = 1.83 

 + (0.756 log W) ±0.05, with M in 

 kcal/day and W in kg. Using the con- 

 version factor of 4.8 kcal = 1 liter 

 of O), the whales" metabolic rates 

 compare favorably with that regres- 

 sion line up to a body weight of 3,000 

 kg. but diverge significantly there- 

 after. The last metabolic rate mea- 

 sured was 16.8 l/min. while the cal- 

 culated value from Kleiber's equation 

 is 6.8 l/min. It is notable that metab- 

 olism in Gigi II. Benedicts elephant, 

 and Irving's whale all differ from 

 Kleiber's prediction, thereby raising 

 the question of whether large mam- 

 mals do indeed follow the 0.75 power 

 rule. However, the value for the 

 70.000 kg fin whale was extrapolated 

 from a measurement in a porpoise 

 (Irving. Scholander. and Grinnell. 

 1941). and neither the elephant nor 

 our whales were studied under condi- 

 tions meeting Kleiber's criteria of 

 ambient temperature neutrality, adult- 

 hood, and basal postabsortive state. 

 The resulting errors would be in the 

 direction of the observed differences. 

 Divergence from the 0.75 power rule 

 may also be seen in growing cattle, 

 horses, children, and rodents (Brody. 

 1964). 



During the phase of rapid weight 

 gain. Gigi II ate from about 1.200 to 



about 1.800 pounds of squid per day, 

 and gained weight at the rate of 

 about 980 kg/mo. If we assume thai 

 squid are about 80 percent water 

 and the dry weight is equivalent to 5 

 kcal/gm (R. Lasker. pers. comm.). 

 and make the further assumption that 

 growing whale tissue contains the 

 same energy (1.720 kcal/kg wet 

 weight) as other growing mammalian 

 tissue (Mayer. 1949), it is possible 

 to calculate the gross efficiencies for 

 growth of a baleen whale calf of 10.3 

 percent and 6.9 percent. Correcting 

 for metabolic rates of 11.0 and 16.8 

 liters O'/min yields net efficiencies for 

 growth of 12.0 percent and 8.0 per- 

 cent (Brody. 1964). In general, growth 

 efficiency is independent of body size 

 (Kleiber. 1947), but is a diminishing 

 function of metabolic age: the calculat- 

 ed values are within the expected 

 range for terrestrial mammals beyond 

 the first doubling of body weight 

 (Brody, 1964). 



Tidal volume equalled about 50 

 percent of resting lung volume, ir- 

 respective of age or size. This is a 

 smaller ratio than that reported for 

 other diving mammals (Irving et al.. 

 1941; Olsen et al.. 1969; Scholander, 

 1940), although they were mature. 

 The ratio of wasted ventilation to 

 tidal volume (VjjVj) in Gigi II was 

 about 13 percent, irrespective of age. 

 This value is consistent with observa- 

 tions in mature diving mammals (Ir- 

 ving et al., 1941; Scholander. 1940. 

 and Kooyman. pers. comm.). and is 

 considerably smaller than the ratio in 

 terrestrial mammals. However. I'j/ 

 Vj diminishes with increasing I'^ in 

 humans and dogs (Bouhys. 1964). a 

 pertinent observation in view of the 

 relatively large V^ in the divers. 



Fluctuations in arterial Pq and 

 A:02 *''h respiration have been pre- 

 dicted in man and terrestrial animals 

 (Otis. 1964; Suwa and Bendizen. 1972) 

 and diving animals (Irving et al.. 194 I). 

 Those fluctuations are influenced by: 

 1) the relative sizes of the tidal and 

 resting lung volumes; 2) the relation- 

 ship between resting lung volume and 

 metabolic rate; 3) the relationship 



