Atavism in Guinea-Chicken Hybrids 725 
of finer texture than the corresponding feathers of the cock. A 
longitudinal median fold bearing mostly minute white feathers 
hangs from below the throat as in the guinea. Although all five 
of the hybrids are male none bears spurs. ‘The legs are strong and 
the metatarsus of each individual bears a few small feathers along 
the outer side but much more sparsely distributed than the cor- 
responding feathering of the male parent. 
The breeder has assured me that when young they resembled 
young guineas but, with advancing age, came more and more 
toward an intermediate condition. I secured them shortly before 
they were three years old. ‘Three of them were killed at the age 
of three years, one at the age of six, and the other is still (1909) 
alive in the Cincinnati Zoological Garden. Curiously enough the 
two which were kept alive at the Zoological Garden continued to 
approach more closely the chicken (male parent) type and at the 
age of five years and since that time, each has possessed a well 
developed pair of sickle feathers (Plate I, Fig. 4) similar to those 
which are so characteristic of the ordinary domestic cock. Some 
clew to the cause for the late appearance of such characteristically 
individual qualities of the male parent may lie in the fact that in 
hybrids, because of the initial incompatabilities which must 
necessarily exist between the two strange germplasms, the male 
plasm requires time to become adjusted to its new and strange 
environment. ‘This is all the more comprehensible if, as I have 
maintained elsewhere,” it is the egg chiefly which determines the 
fundamental animal form (i.e., such characteristics as are com- 
mon to both the male and female of a given kind of animal), 
although both sperm and egg contribute the individual and specific 
peculiarities of the respective parents. [ may add that a conclu- 
sion similar to this has since been arrived at by Conklin’ as a result 
of his embryological investigations. 
The voice of the hybrid is much louder and even more discord- 
ant than that of the guinea although it bears more resemblance 
to the latter. The hybrids were always extremely wild and never 
2 Guyer, M. F.: Do Offspring Inherit Equally from Each Parent? Science, vol. xxv, no. 652, June 
28, 1907. 
3 Conklin, E.G.: The Mechanism of Heredity. Science, January 17, 1908. 
