2 
The second table is arranged to test de Vries's hypothesis of 
dominance of patent over latent characteristics. As not all of the 
preceding characters can be placed in these two categories, this list differs 
from the last. 
Cliaraoteristic 
Patent Condition 
Latent Condition 
1. 
Nasal process of pre- 
maxillary 
Narrow nostril 
High nostril 
2. 
Cerebral closure 
Flam skull 
Cerebral hernia 
Crest 
Present 
Absent 
4. 
Complete development 
of feather 
Non-silkiness 
Silkiness 
6. 
Plumage pigment 
Black and red 
White (usually) 
(). 
Shafting 
Present 
Absent 
7. 
Pencilling 
Present 
Absent 
This table shows that of the foregoing seven characters six are 
dominant in the patent condition. The exceptional case of white 
pigment is not universally dominant. The result indicates that de 
Vries's law is a valid one where the allelomorphs can be classified as 
patent and latent respectively. The law has, however, this plain hmit 
to its applicability. 
A more general expression of the law of dominance in poultry is this : 
a progressive variation, one which means a further stage in ontogeny 
(whether novel or ancient, and without reference to latency or patency), 
will be dominant ; a variation that is due to abbreviation of the onto- 
genic process, which depends on something having dropped out, will be 
recessive. The following table shows this relation : 
Characteristic 
Progressive Condition 
Arrested Condition 
2* 1 Comb 
r Pea 
\ Rose 
Single 
Single 
3. Nasal process of pre- 
Developed ; narrow nos- 
Undeveloped ; wide nos- 
maxillary 
tril 
tril 
4. Cerebral closure 
Perfect ; plain skull 
Imperfect ; hernia 
5. Crest 
Present 
Absent 
^* 1 Feather-form 
\ Typical ; plain 
\ Frizzled 
Embryonic ; silky 
Plain 
8. Muffling 
Present 
Absent 
9. Skin colour 
Pigmented ; black 
White 
10. Iris colour 
Pigmented ; black 
Eed 
11. Plumage colour 
Pigmented 
Wliite (usually) 
12. Melanic pigmentation 
Melanism ; wholly black 
Eed and black pigmented 
13. Shafting 
Present 
Absent 
14. Pencilling 
Present 
Absent 
Of the foregoing fourteen characters thirteen have the more progressive 
condition of the characteristic dominant. The exception is again plumage 
colour, which is, as stated, not always an exception. 
To sum up, I think the evidence warrants the conclusion that, 
in poultry, dominance of a characteristic in hybridisation is usually 
determined by the same causes as determine the appearance in the race of 
a progressive variation. 
Spcttlswcode (k Co. Lt l., Printer New-'-treet Square, London, 
