32 
Canary Breeding 
and one of a greyish type all much paler than the normally coloured young of 
greenfinches. It is too early to sex the young, but I hope to have, at last, seen a 
male cinnamon greenfinch * ! The cinnamons appear to be males, and the grey a 
female. 
III. Other characters which are seen to behave as recessives are (a) buffness, 
(6) crest-bred plainheadedness, and their corresponding qualities (a) yellowness, 
(h) crestedness, exhibit more or less imperfect dominance. 
There can be no doubt that the majority of crests at present are heterozygous 
with regard to crest, although this cannot be essential to crest formation as stated 
by Bateson (Principles of Heredity, 1909), for the Trumpeter pigeon, which is 
homozygous, has a similar arrangement in its rose crest (Plate V, fig. 6). Bateson 
also, following Davenport, is in error in assuming that the fancier's bald crest is an 
upstanding crest which shows the bald occiput. Such a crest is the very reverse 
of bald, and is the well-known " mop " crest of the fancy, 
IV. My points of disagreement with 0. B. Davenport centre mainly in the 
material used in his experiments, and in his interpretation of fancy points with 
regard to crest and plumage colour. 
His " green x yellow " matings do not correspond with my " green x clear " 
partly because his " green " is not green but variegated {vide Plate I. fig. 1, where the 
pied throat shows the bird to be variegated). Similarly nearly all " clears " have 
dark underflue, or dark spots on bill or feet, which strictly constitutes them varie- 
gated. Hence Davenport's "green x yellow" is really variegated x variegated, and 
naturally from this mating one would expect variegated or " mottled " young. 
Moreover, greens often become variegated, variegateds often become ticked, and 
ticked birds often become clear during their life-time. 
Davenport's perfect crest, as has been shown, is far short of what is considered 
perfect at the present day, and the perfect crest does not depend on the absence of 
a bald occiput. 
The technical qualities " yellow " and " buff" are important in any study of the 
plumage of the canary, and are not considered. 
V. It is essential in studying Mendelian phenomena as occurring in fancy 
varieties that the most strict definition of the characters under examination be 
made, and that their nomenclature, and behaviour under varying conditions, be 
thoroughly understood. A fancier is trained to detect differences which others are 
quite unable to see, and his success depends on the careful balancing of factors 
which to the uninitiated are unobservable. It would therefore save much confusion 
if sharply defined facts only were taken into consideration meantime, and if no 
assumptions were made such as those referring to " bald occiput," " baldness," 
" perfect crest," etc. 
An expression of my deep indebtedness is due to Professor Karl Pearson, for 
much assistance and advice in the preparation of this paper. 
* Three of the cinnamons died, and on examination were found to be males. 
