APPENDIX 
into the first generation of feathers correspond to the 
papillae which in lizards develop into scales? 
“The late Professor Assheton, who undertook the ex- 
amination of some of the material brought home by the 
Terra Nova, madea special study of the feather papillae of 
the Emperor Penguin embryos from Cape Crozier. Draw- 
ings were made to indicate the number, size and time of 
appearance of the feather papillae, but unfortunately in 
the notes left by the distinguished embryologist there is 
no indication whether the feather papillae were regarded 
as modified scale papillae or new creations resulting from 
the appearance of special feather-forming factors in the 
germ-plasm. 
“When eventually the three Emperor Penguin em- 
bryos reached me that their feather rudiments might be 
compared with the feather rudiments of other birds, I 
noticed that in Emperor embryos the feather papillae ap- 
peared before the scale papillae. Evidence of this was espe- 
cially afforded by the largest embryo, which had reached 
about the same stage in its development as a 16-days goose 
embryo. 
‘In the largest Emperor embryo feather papillae occur 
all over the hind-quarters and on the legs to within a short 
distance of the tarsal joint. Beyond the tarsal joint even in 
the largest embryo no attempt had been made to produce 
the papillae which in older penguin embryos represent, 
and ultimately develop into, the scaly covering of the foot. 
The absence of papillae on the foot implied either that the 
scale papillae were fundamentally different from feather 
papillae or that for some reason or other the development 
of the papillae destined to give rise to the foot scales had 
been retarded. There is no evidence as far as I can ascer- 
tain that in modern lizards the scale papillae above the tarsal 
joint appear before the scale papillae beyond this joint. 
‘The absence of papillae below the tarsal joint in Em- 
peror embryos, together with the fact that in many birds 
each large feather papilla is accompanied by two or more 
very small feather papillae, led me to study the papillae of 
the limbs of other birds. The most striking results were 
