432 Data on Variation in the Comb of the Domestic Fowl 
many degrees." In a further paragraph, he says : " In later life the distinction 
between intermediate and single may become very obvious ; but even though the 
comb may grow up to some height, the three ridges of the pea comb remain 
marked. The intermediate pea comb in both sexes usually lies either on one 
side or the other, like that of the Leghorn hen." The existence of intermediates 
between these comb types has been confirmed by Davenport {loc. cit), who says 
(p. 35), in discussing the comb form of B. Minorca x Brahma hybrids : " In all 
cases the pea comb of the Brahma dominates over the single comb. Critical 
examination shows, however, that the pea comb of the hybrid is not always typical. 
Frequentl)' the whole structure, and especially the median ridge, is abnormally 
high (Fig. 21), and, on the other hand, in a few cases the lateral ridges are hard 
to make out. The dominance is imperfect." Such intermediates between single 
and pea combs are very well shown in Davenport's Figs. 20 and 21. 
We have obtained the same result in our own hybridizing experiments with 
single and pea comb crosses. In the Fi hybrids the combs frequently are high 
and have a deeply serrated dorsal border. Such a condition is never found, so far 
as we are aware, in fowls pure bred in respect to pea comb. At the same time, 
these hybrid birds exhibit unmistakable traces of the lateral ridges which are 
typical of the pea comb. It would be hard to conceive of a more perfect inter- 
mediate form between the pea and the single comb type than is afforded by 
such birds. 
Summarizing the facts brought out by the inventory of qualitative variations 
exhibited in these combs it may be said that there appears to be continuous varia- 
tion, considerable in amount, in every definable characteristic of the comb. All 
degrees of intergradation between the extreme conditions of each of these charac- 
teristics regularly occur. 
EXPLANATION OF PLATES. 
All figures are reduced to one-third. 
Plate I. Outlines of Combs 1 to 35. 
Plate II. Outlines of Combs 36 to 71. 
Plate III. Outlines of Combs 72 to 96. 
