DEPARTxMENT OF EXPERIMENTAL EVOLUTION. 115 



Inbreeding and Degeneration of Rats, hy G. C. Bassett. 



Dr. G. C. Bassett, who has been working, under the direction of 

 Professor John B. Watson, at Johns Hopkins University, upon the 

 consequences of inbreeding on the intelHgence of rats, is temporarily 

 attached to this Station and continuing his work here. His early 

 investigation showed that after four generations of closest inbreeding 

 (brother and sister within the litter) there was a loss in brain weight 

 of from 7 to 10 per cent on the average and a loss in ability to form 

 habits of about 30 per cent on the average; but no further important 

 degeneration of the stock occurred, even to the tenth generation of 

 inbreeding. Dr. Bassett's conclusion that on the average inbreeding 

 is accompanied by deleterious effects upon the brain and intelligence 

 accords with results obtained at this Station on the deterioration in 

 the yield of maize upon self-pollination. Dr. Bassett proposes now 

 to establish in the white rat a condition analogous to that of imbe- 

 cility in man; to produce through inbreeding and selection a strain 

 of rats of inferior intelligence, and to use this, in hybridization experi- 

 ments, to test the inheritance of such mental inferiority. He proposes 

 to study, at the same time, the effects of chronic parental alcohohsm 

 upon the progeny. This will comprise a study of brain and cord 

 weight, blood and kidneys, and the intelHgence. 



The foregoing experiments are closely related to those begun at 

 Goose Island by the Wistar Institute. Those experiments were dis- 

 continued by the Wistar Institute, as the evidence showed, first, that 

 the albino rats could not survive alongside of the brown rats of the 

 island, and, second, that the mere trapping of brown rats on Goose 

 Island may not exterminate them, as there is evidence that the 

 island is subject to invasion by rats from larger islands and those 

 nearer the mainland. In the early spring (April) rats are absent or 

 rare, but they have been trapped in large numbers during June every 

 year since we have had the island. 



Studies in Human Heredity, hy C. B. Davenport. 



That part of the Director's studies relating to the results of experi- 

 ments in heredity that man is making on himself is comprised under 

 the name Eugenics Record Office. This aspect of the work has 

 received continued generous support from Mrs. E. H. Harriman and 

 Mr. John D. Rockefeller. Its board of scientific directors includes 

 Alexander Graham Bell, William H. Welch, Lewellj^s F. Barker, 

 Irving Fisher, E. E. Southard, and C. B. Davenport. 



The principal investigations now being conducted are: (1) the 

 consequences of human inbreeding in an island population; (2) the 

 consequences upon the physical and mental traits of a blood fine, 

 formerly highly inbred and very neurotic, but which for a generation 



