APPENDIX 
obtained from the embryos of Chinese geese in which the 
legs are relatively longer than in penguins. In a 13-days 
goose embryo the whole of the skin below and for some 
distance above the tarsal joint is quite smooth, whereas the 
skin of the rest of the leg is studded with feather papillae. 
On the other hand, in an 18-days goose embryo in which 
the feather papillae of the legs have developed into fila- 
ments, each containing a fairly well-formed feather, scale 
papillae occur not only on the foot below and for some dis- 
tance above the tarsal joint but also between the roots of 
the feather filaments between the tarsal and the knee joints. 
More important still, in a 20-days goose embryo a number 
of the papillae situated between the feather filaments of the 
leg were actually developing into scales each of which over- 
lapped the root (calamus) of a feather just as scales overlap 
the foot feathers in grouse and other feather-footed birds. 
‘‘ As in bird embryos there is no evidence that feather 
papillae ever develop into scales or that scale papillae ever 
develop into feathers it may beassumed that feather papillae 
are fundamentally different from scale papillae, the differ- 
ence presumably being due to the presence of special 
factors in the germ-plasm. Just as in armadillos hairs are 
found emerging from under the scales, in ancient birds as 
in the feet of some modern birds the coat probably con- 
sisted of both feathers and scales. But in course of time, 
owing perhaps to the growth of the scales being arrested, 
the coat of the birds, instead of consisting throughout of 
well-developed scales and small inconspicuous feathers, 
was almost entirely made up of a countless number of 
downy feathers, well-developed scales only persisting be- 
low the tarsal joint. 
“Tf the conclusions arrived at with the help of the 
Emperor Penguin embryos about the origin of feathers 
are justified, the worst journey in the world in the interest 
of science was not made in vain.” 
END OF VOLUME ONE 
Printed in Great Britain by R. & R. CrarK, Limirep, Edinburgh. 
