DEPARTMENT OF EXPERIMENTAL EVOLUTION. 129 



tall woman occurred only once, or one-tenth the expected number of 

 times, while the marriage of a very tall man to a very short woman did 

 not occur at all. 



Hereditary traits of naval men. — The Director, assisted by Miss 

 Mary T. Scudder, has analyzed the juvenile and family history of naval 

 officers representing 65 families and including over 100 naval officers of 

 various grades. The result has been the formulation of a new method 

 which may be utiUzed in the selection of naval officers, namely, the con- 

 sideration of the facts of juvenile promise and family history. It is 

 found that naval officers are of different types; there are naval fighters 

 (Uke Nelson, Farragut, Porter, and Gushing) , naval explorers (hke Sii- 

 John Frankhn, McClintock, and our own Wilkes), naval inventors 

 (like Dahlgren), naval diplomats (like Hornby), and so on. To con- 

 sider the fighters only, one finds nomadism, love of the sea, hyper- 

 kinesis, and absence of fear practically universal, even at a very early 

 age. The hyperkinetic tendency shows in either father or mother; if 

 in both it tends to be exaggerated in the son. The factors for the 

 nomadic and adventurous traits usually come from the maternal germ- 

 plasm only, though, in consequence of the fact that young naval officers 

 frequently marry young women of naval stock, the traits may be shown 

 in both sides of the house. It is concluded that the strong inclination 

 toward the sea depends upon a recessive factor. 



HEREDITY IN SHEEP AND POULTRY. 



The experiments on heredity of twinning, multinippling, and pro- 

 duction of a superior strain in sheep have been continued. At the 

 station 22 lambs were bom from 13 mothers, not quite so good a record 

 as last year. The cooperative sheep experiment with the New Hamp- 

 shire Experiment Station is being continued. A paper on "Family 

 performance as a basis for selection in sheep" was pubUshed conjointly 

 with Mr. E. G. Ritzman, animal husbandman at the New Hampshire sta- 

 tion. Progress is being made with the poultry strains. During the year 

 338 chicks were hatched, mostly of ''new buff" and ''bareneck" strains. 



EXPERIMENTAL PRODUCTION OF VARIATIONS. 

 COLORATION OF CAVE SPECIES IN SUNLIGHT. 



Gave-inhabiting amphipods are without pigment and appear of an 

 opaque white, nor will they gain pigment when exposed to sunUght. 

 The young of one species from the caves of southern Indiana have been 

 reared by Dr. Banta in dayhght and gained a brownish-pink colora- 

 tion. This color does not depend on chromatophores, nor does it he 

 in definite granules. Its significance remains undetermined, though it 

 is clear that the light has induced some physiological change that leads 

 to the production of a diffuse pigmentation. 



