HEREDITY OF PIGMENTATION 171 
5. A similar ease of blended inheritance, described by Newman 
for the time of first appearance of head pigmentation, was found 
to be actually a case of the combination of two crops of head chro- 
matophores. The second crop appears in both species and hy- 
brids The first crop is present in F. heteroclitus and both hy- 
brids and hence its presence is a dominant in the Mendelian sense. 
6. Immediately after hatching the characters which have served 
to distinguish the four forms begin to disappear so that after 
a few months both pure species and the hybrids look practically 
alike. . 
All camera drawings from living fish. The opaque red chromatophores are 
figured in red. Dotted lines indicate blood vessels. H=heart. 
Fig. 1 Pure F. heteroclitus, four days old, showing first chromatophores. 
S< 25), 
Fig. 2. Pure F. heteroclitus, three and one half days old, circulation started 
not more than a few minutes before drawing began. X 25. 
Fig. 3 Brain of same embryo drawn in fig. 2 but three and one half hours later. 
* 25. 
