14 Result of Crossing Japanese Waltzing with Albino Mice 
It is not suggested that the remarks here offered prove an agreement between the 
results obtained and those which follow from the law of ancestral heredity. It is 
contended that the experiment confirms a result, already obtained by Cuenot, that the 
ancestry of albinos is a factor in determining the characters of the young produced 
when albino and coloured mice are crossed ; it is contended that this result makes 
it impossible to regard albinism as a character which is transmitted in a state 
of " gametic purity " by every individual which exhibits it ; and therefore since 
the ancestry of albinos has to be taken into account in predicting their behaviour 
when ciossed, some law of ancestral heredity must be formulated. The present 
data do not enable us to determine the correlations between parent and offspring 
with sufficient accuracy to say whether the Galton-Pearson law will fit this case 
as it fits so many others ; but they do enable us to say that the sign of these 
correlations — the first negative coefficients of direct parental inheritance yet 
published — is in accordance with that law, and that the results obtained do not 
demonstrably contradict it in other respects. 
Offspring of Hybrids. 
Hybrids have been paired together or crossed with albinos; a third group of 
unions between hybrids and extracted albinos may perhaps be treated as belonging 
to this generation. The results of these three kinds of unions will be considered 
separately. 
Offspring of hybrids paired together. 
The unions of hybrids gave altogether 555 young ; which were divisible into 
three groups according to the characters of the eyes and coat : these were 
Albino 137 
Coloured or piebald with dark eyes 287 or 28-i* 
Coloured or piebald with pink eyes 181 or 134 
555 
Dividing these mice according to their mode of walking we find that there are 
Waltzing 97 
Normal 458 
555 
It is clear that the albinos occur in this generation with a frequency indicated 
by a purely Mendelian theory of albinism regarded as a simple unit character, 
* There is unfortunately a doubt concerning the eye-colour of three mice ; these are all lilac in 
colour, and I am practically sure that they had pink eyes. I have never observed a lilac mouse which 
had dark eyes; the omission of the letter after the lilac mice catalogued in my second paper (Biometrika, 
Vol. II. Part 2, pp. 168, 169) is due to inadvertence in proof reading. 
