434 



SCIENCE. 



[N. S. Vol. XXIII. No. 585. 



species; while with complete isolation more 

 or less divergence may result before diversity 

 of selection comes in to intensify the segre- 

 gation. 



Of selection I also discover many reflexive 

 forms due to the influence of members of the 

 same species upon each other, as well as nat- 

 ural selection and artificial selection due to 

 influences lying outside of the species. 



In considering the factors producing dif- 

 ferent inheritable types of related organisms 

 we have to distinguish between the factors 

 dividing the original stock into separate inter- 

 generating groups and those producing di- 

 versity of inherited character in the separate 

 groups. The former process we may call 

 racial demarcation through isolation, and the 

 latter racial intensification through survival 

 resulting in selection. Isolation and selec- 

 tion we find to be cooperating factors in con- 

 trolling racial segregation. 



Our investigation of the factors producing 

 evolution will, however, remain very incom- 

 plete unless we study the influences producing 

 different social groups, in which different 

 habits of dealing with the environment are 

 originated and maintained, not by variation 

 and heredity, but by innovation and tradition. 

 Here again we must distinguish between the 

 influences dividing the original group into 

 separately associating groups, and those that 

 establish a diversity of habits and acquired 

 characters in the separate groups. The former 

 process we may call habitudinal demarcation 

 through partition and the latter habitudinal 

 intensification through success resulting in 

 election. Partition and election we find to be 

 cooperating factors in controlling habitudinal 

 segregation. 



In the bionomic history of many species 

 the great significance of habitudinal segrega- 

 tion is found in the fact that it is the fore- 

 runner of racial segregation. 



For illustrations of the influence of hab- 

 itudinal segregation on racial segregation I 

 would refer to my work on evolution published 

 by the Carnegie Institution. 



John T. Gulick. 

 Oakland, Cal. 



SALMON HYBRIDS. 



To THE Editor of Science: I have received 

 from Mr. C. W. Dorr, of the Alaska Packers' 

 Association, certain notes by Mr. J. A. Eich- 

 ardson on experiments in hybridization of 

 salmon, undertaken in the hatchery at Kar- 

 luk, Alaska. These will be of interest to 

 zoologists. David Starr Jordan. 



Mr. Eichardson writes as follows: 



Crosses have been made of all of the salmon 

 family except the steelhead. These experi- 

 ments have been made for the novelty of it. 

 The peculiarities of each are invariably the 

 same from year to year, and practically none 

 of the fry survive. 



The cross between the red salmon and king 

 salmon produces a very queer lot. Out of 

 many thousand eggs hatched, ninety per cent, 

 of the fry will have no eyes; the nose is long 

 and pointed; the sac is of very light color and 

 quite watery in appearance. Only two per 

 cent, or three per cent, are reasonably well 

 formed fish, and the most of these die. 



The number of eggs which fertilize is about 

 normal, but it is noticed that a larger number 

 than usual of the white eggs removed from 

 the baskets contain embryos that have ceased 

 to develop. This cross has been made both 

 ways. 



It has been demonstrated that the cross be- 

 tween the red salmon male and the humpback 

 female is very superior to other crosses — so 

 much so that it leads to the belief that there 

 is closer relationship between these two species 

 of the salmon family. An extended experi- 

 ment by crossing these two species is now be- 

 ing carried on. The loss of eggs and fry is 

 being counted and notice taken of general 

 conditions. We have fine specimens from the 

 season 1904 (eggs taken in 1903) of this cross. 

 They are about eight months old, two inches 

 long, and bright, clean, silvery fish, rather 

 long and slim. 



SPECIAL ARTICLES. 

 an interesting discovery of human imple- 

 ments IN AN abandoned RIVER CHANNEL 

 IN SOUTHERN OREGON. 



During July and August, 1905, the writer 

 was in the field in southern Oregon under the 



