66 “TERRA NOVA” EXPEDITION. 
(37 days), and in No. 7 nest on December 27th (33 days), whilst in another case, 
in which observations were most carefully made, the period was only 31 days. This 
seems to show that the incubation of the embryo does not invariably begin as soon 
as the egg is sat upon, as the observations were most carefully made and recorded, 
each nest, as I have said, being marked and visited daily. 
The following table enables a comparison to be made between my own results and 
those of Wilson and Bernacchi :— 
Wilson. Bernacchi. Levick. 
First egg laid : . 5 : Middle of November Nov. 2nd Noy. 3rd 
Chick hatched. é : : Middle of December Dec. 9th Dec. 4th 
Nestling’s down moulted : : Jan. 9th to 16th. 
Not until the eggs have been laid does either of the birds go to feed. Then one 
of the pair goes off to the water for this purpose, and stays away in many cases 
for some days (about 7 to 10), after which it returns to relieve the other, who goes 
off for about the same period. Then, when the chicks are hatched, they relieve one 
another at more frequent intervals, as seen by the time-table given on pp. 67, 68. 
A most astonishing fact is the long fast which the birds undergo between 
their arrival at the rookery and the hatching of the chicks, the shortest period of 
this total abstinence being about 18 days; but as the first of the pair to go off 
to feed remains away in many cases for ten days, the other must fast for about 
28 days. 
This fact, occurring as it does during the most arduous period of the penguins’ 
year, furnishes a most surprising proof of the wonderful endurance possessed by these 
birds. They arrive tired after their journey to the rookery. In the case of the 
cocks, they go through a long period of repeated battle and continual anxiety. They 
propagate their species, and work to gather stones for their nests, yet for 28 days 
they eat nothing at all, and at the end of that time, though dirty and bhedraggled, 
they seem little the worse for it. 
The reason for this fasting is, perhaps, partly that they dare not leave their nests 
unprotected during the early part of the season, when building is in progress all 
around, and stones are in great request ; and also because, as I have already remarked, 
until the eggs have come, strange cocks frequently make overtures to hens who are 
already mated, and thus the cock can only ensure the safety of his home by his 
constant protection. 
Consequent on the penguins’ abstinence from food, no guano is deposited about 
the rookery until the eggs have been laid, and so the brick-red colouring of the rookery 
described by previous authors is not seen during the early part of the season. 
Instead of this, bright green watery excreta are dropped, consisting of bile, water, 
salts, and epithelial cells (the bile of penguins is bright green). The bird as it sits on 
its nest never fouls this, but squirts its excreta well clear of its walls. This taking 
