26 EDWARD A. WILSON. 



in this case be tending to whiteness would be either of the extremes of temperature, 

 and should be better exemplified by Polar and Tropical species than by those of 

 Temperate regions. One other suggestion I would make, namely, that it is an economy 

 to a bird or beast to produce white or unpigmented feather or hair, when such feather 

 or hair has not necessarily got to stand much wear and tear. White feathers 

 undoubtedly wear out far more quickly than pigmented feathers ; as, for example, in 

 the moulted primaries of our common Herring Gull (Larus argentatus), where the result 

 of wear and tear on pigmented and unpigmented parts of the same feather may readily 

 be seen, and perhaps even better still in the feathers of the Curlew (Numenius 

 arquatus) (fig. 46, p. 104). 



With the hope of throwing light on the rate of growth of the young Emperor 

 Penguin chickens, we took two on September 13th, 1903, the largest we could find 

 in the rookery, back to the ship. 



On September 20th these weighed respectively 636 and 662| grms. The less 

 heavy of the two, which survived until December 10th, increased at the following 



rate : 



September 3rd, 1908, probable date of hatching, probable weight 450 grms. 



20th 636 



27th 889 



October 4th 1247-5 



llth 1452 



18th 1610 



25th 1865 



November 1st ... over 2000 



(NOTE. 453 grms. = 1 Ib.) 



We weighed also several others taken on different dates, for example : 



No. 16. Immature in down, found dead. Sept. 13, 1903 ... weighed 453 grms 



No. 1. taken alive. Oct. 18, 1903 ... 1698-75 



No. 2. taken alive. Oct. 18, 1903 ... 1812 



No. 3. found dead. Nov. 2, 1903 ... 1670-4 



No. 4. taken alive. Nov. 5, 1903 ... 1245-75 



The weight of a large egg (No. 34), slightly incubated, was just short of 1 Ib. 

 (448-5 grms.). 



Probably for the first month or two of its life each chicken puts on rather more 

 than half a pound per week, but in its third and fourth months this average must be 

 largely increased, for in January the chick reaches a bulk equal to about half that of 

 an adult bird, and probably weighs as much as 30 Ibs. 



The voice of the chick is a very shrill rattling pipe or whistle when it is hungry. 

 First it lowers its head to the ground, craning the neck to its full extent, and then 

 suddenly swings it up as far as it will go, rattling out a very shrill piercing whistle of 

 four notes. It is a crescendo pipe, rising in pitch and in shrillness and suddenly 

 dropping at the end note. Out on the ice in the open air the rookery sounds as though 

 it were full of farmyard chickens. In a confined cabin the noise, even of two 



