HEREDITY OF PIGMENTATION Loa 
tophores of the lateral line, and the arrangement of the black yolk 
chromatophores, where incomplete dominance is associated with 
differences in rate of development. Newman’s results also 
point in the same direction, though he does not mention this con- 
trast between the absence of dominance in characters connected 
with the rate of development and the presence of dominance in 
other characters. Thus most of the characters which Newman 
investigated were concerned with the rate of development and 
in most of them he found ‘blended heredity.’ Thus we see that 
in general characters connected with the rate of development 
show blended heredity, and it may be that such characters are 
so intimately connected with extra nuclear substances such as 
the yolk that complete dominance is not obtainable. 
LATER DEVELOPMENT 
This later development concerns only the two parent species 
and the: F. heteroclitus egg hybrid for the F. majalis egg hybrid 
was never found to live longer than two days after hatching. 
Newman found that none of this form hatched; but in these exper- 
iments, usually a few fish hatched in each series, perhaps a dozen 
in all. In all of these the hatching seemed premature, the yolk 
sac had not been absorbed, and the fish died a little later. 
In the other forms the chromatophores began to contract shortly 
after hatching, probably because they then came under the influ- 
ence of the nervous system. As the amount of contraction varied 
with the environment, and with the condition of the fish, close 
comparison of color patterns, and of size and shape of the chroma- 
tophores was no longer possible. The motions of the fish, for 
it was usually not safe to risk narcotization, also made exact 
comparisions difficult, I think, however, that it may be safely said 
that the only changes that have taken place since hatching are 
all in the direction of making the three forms more like each other, 
until at the present time, three months after hatching I can 
find no characters which will distinguish any one form from the 
other two. They all have developed much more pigment of the 
black and greenish yellow kinds, especially in the dorsal region; 
