June 19, 1908] 



SCIENCE 



941 



perimental Evolution, Cold Spring Har- 

 bor, N. Y. 



Genetics in Swine Hyhrids: Q. I. and J. 



P. Simpson, Pabner, 111. 



In the year 1896 the writers began ex- 

 periments with swine for economic results 

 and for determining the relative potential 

 of sex; but the uncovering of Mendel's 

 laws has since broadened our inquiry. 



The material has comprised nine pure 

 and distinct breeds. 



Two breeds, although of identical color, 

 do not act alike under hybridization, show- 

 ing a difference in their color determiners. 



Combinations are made where coat color 

 is full dominant, but skin color complete 

 recessive, in the same animal. 



We find the wild sus scrofa full domi- 

 nant over every observable character and 

 instinct of the Tamworth— even fooling 

 the naturalists. 



The solid hoof of the "Arkansas Mule 

 Foot" is dominant over normal breeds; 

 but intermediate grades of hoof are made 

 at will. 



Examples are shown of a transferrence 

 of color, following shedding of the hair ; of 

 finely mingled roans ; of segmented color- 

 ing of individual hairs (like the banded 

 hairs of the wild Texas peccary), all show- 

 ing that two colors may exist in the same 

 cell — one of them passively awaiting its 

 biochemic stimulus. 



Instances are noted of the testes acting 

 as this stimulus and, from the apparent 

 mass of evidence, that color may exist in 

 cells, unexhibited, is drawn a conception 

 that seems to emasculate the "allelomorph 

 to its absent" theory, now held by some 

 renowned experimenters. 



Of two red breeds, identical in tint, 

 crossed with a white breed, one produces 

 roans only; while the other makes only 

 mosaics, showing that the first red breed is 

 of solid color origin, and the last, of pat- 



tern origin. And the known history of 

 each confirms this. 



Color quantity in the individual is in 

 ratio to the sum of its parents' colors. 



A cause for the white belt in horse, 

 swine, ox and India tapir is thought to be 

 embryonic, and its more anterior location 

 on swine is ascribed to blastomere diver- 

 gence between these species. 



Among the nine breeds used in hybrid 

 experiments, it was discovered that some 

 breeds would pair with equal color-poten- 

 tial. And the broods from these exhibit 

 two distinct classes, equally divided, indi- 

 cating the slightly inexact division of a 

 chromosome in the oogenesis or spermato- 

 genesis of a parent; and when confirmed 

 by further experiment will show a fruitful 

 cause for variation, within a breed or 

 species. 



We have found to be absolute, the Men- 

 delian reseparation of units in swine color- 

 hybrids. 



When we say that with morphologic and 

 color units the breeder may now add, com- 

 bine and fuse, can extract, precipitate and 

 analyze for purity— as with chemicals — 

 that he may almost create designs at wiU, 

 it is not said in egotism; but in profound 

 acknowledgment to you men of science who 

 show the way. And whilst the breeder's 

 interest is not uppermost in your research 

 of nature's evolution, his gratitude is none 

 the less. 



Report on Some Experiments in Trans- 

 planting Species of Leptinotarsa into 

 new Habitats, with Remarks upon the 

 Significance of the Mode: W. L. Tower, 

 University of Chicago. 



Inheritance of Crest and Color in Cana- 

 ries: C. B. Davenport, Carnegie Station 

 for Experimental Evolution, Cold 

 Spring Harbor, New York. (Published 

 in Proceedings of the Eastern Branch.) 



