DEPARTMENT OF EXPERIMENTAL EVOLUTION, 83 



been testing the pure-line theory by the use of beans — the same kind of 

 plants that Johannsen used in his fundamental experiments. Many of Dr. 

 Harris's records go back to 1905, and they afford excellent material for a 

 critique of the pure-line theory. We may expect an early publication of 

 these data. 



QUANTITATIVE STUDIES OE SELECTIVE ELIMINATION. 



An outline of these studies, which are being made by Dr. Harris, appeared 

 in Year Book Xo. 9. Since that report it has been shown that the elimination 

 of ovaries demonstrated in Staphylea is probably not due to the combination 

 of such simple factors as a differentiation of the ovaries associated with their 

 position on the inflorescence and a proportionally higher but random failure 

 of the ovaries situated in the more distal regions of the inflorescence. It 

 seems, therefore, that failure to develop must depend upon some innate 

 unfitness with which definite structural peculiarities are associated. 



Dr. Harris has instituted several studies to obtain further light upon these 

 questions. Tests with other species are being made to determine whether 

 the results found for Staphylea are at all general. Other criteria of func- 

 tional unfitness are being sought. But the problem is so complex — involving 

 so many factors which may often screen each other's influence — that it can 

 not now be discussed in greater detail. 



INFLUENCE OE BECOMING FERAL ON DEVELOPMENT OF THE NERVOUS 

 SYSTEM OF A DOMESTIC ANIMAL. 



The acquisition of Goose Island has permitted this Station to begin an 

 important experiment on the changes that a domesticated species undergoes 

 in becoming feral. Last year, as already reported, in cooperation with Prof. 

 H, H. Donaldson and the Wistar Institute of Anatomy and Biology, an at- 

 tempt was made to kill oft' the brown rats and to colonize the island with 

 white rats (June 21, 1910). On July 21 of this year Dr. Hatai, of the 

 Wistar Institute, visited the island, set two dozen spring traps, mostly along 

 the western bank, where there are many holes. Not a single albino rat was 

 caught, but, instead, 8 brown rats {Miis novegicus) of various sizes. Thirty- 

 four albino rats, each having its ears marked for future identification, were 

 then liberated on the island. 



On July 17 Dr. Hatai and myself visited Goose Island to see if the albino 

 rats had established themselves. Two female albinos with marked ears were 

 found dead from severe wounds, as though bitten to death by rats. At this 

 time, in broad daylight, no living albino rats appeared on the island ; and 

 this is the more noteworthy since the liberated rats were very tame. Dr. 

 Hatai then set four traps, two along the western bank, where most of the 

 Norway rats had been caught, and two behind the house at the southern end 

 of the island. 



