408 H. H. NEWMAN 



characters. The different characters of these cells behave as 

 though they were Mendelian unit characters that are shuffled 

 and dealt out in all possible combinations. Some cells show 

 the maternal character of squarish body plus the fine branches 

 characteristic of the paternal species. Branching cells in hy- 

 brids also fuse into syncytia and nonbranching cells remain 

 isolated. A field of chromatophores (fig. 4) is essentially a mosaic 

 of paternal and maternal characters, and to explain the situation 

 one must call upon the somewhat overworked idea of somatic 

 segregation, or else make use of the hypothesis of regional alter- 

 native dominance, which is, in last analysis, dependent on somatic 

 segregation. 



The red chromatophores of Fundulus and the green ones of the 

 mackerel are not homologous structures and are in no sense alle- 

 lomorphs of each other. One never finds any mixing of the char- 

 acters of these two types of cell. They are absolutely distinct 

 and opposite, and each is quite characteristic of the species to 

 which it belongs, for Fundulus never has any green chromato- 

 phores nor the mackerel any red ones. It will be obvious, then, 

 that we have the ideal situation for demonstrating paternal 

 inheritance. If we find in a hybrid between these two species 

 the characteristic chromatophores of the paternal species, the 

 controversy as to the pure maternal character of heterogenic 

 hybrids is at an end. The presence of abundant green chromato- 

 phores in a hybrid based upon a Fundulus egg proves that the 

 hybrid inherits this character from the paternal species, the 

 mackerel. This is not a doubtful matter or a sporadic occurrence, 

 but a result that anyone can obtain any time he crosses Fundulus 

 heterochtus 9 X Scomber scombrus cT toward the middle of 

 June. If the cross is made two weeks later it will be difficult to 

 find the green chromatophores. 



The correlation between success in development and the strength 

 of paternal inheritance 



It has been pointed out that in this cross, as well as in a con- 

 siderable number of other heterogenic crosses, that the most 



