author's abstract of this paper issued 

 by the bibliographic service march 2 



STUDIES ON INBREEDING 



I. THE EFFECTS IN INBREEDING ON THE GROWTH AND VARIA- 

 BILITY IN THE BODY WEIGHT OF THE ALBINO RAT 



HELEN DEAN KING 



The Wistar Institute of Anatomy and Biology 



The rapid development of the new science of genetics has 

 opened up many fertile fields of investigation and it has also re- 

 vived interest in the problem of inbreeding which has been dor- 

 mant for many years. Charles Darwin ('75, '78) considered the 

 subject of inbreeding so important that not only did he collect 

 all available data regarding it, but he himself carried on a series 

 of inbreeding experiments that extended over a period of eleven 

 years, Darwin's experiments on plants were followed by those 

 of Crampe ('83), of Huth ('87), and of Retzima-Bos ('93; '94) on 

 various species of mammals. The conclusions reached by each 

 of these investigators can well be stated in the words of Darwin 

 ('78): "The consequences of close interbreeding carried on for 

 too long a time, are, as is generally believed, loss of size, con- 

 stitutional vigor and fertility, sometimes accompanied by a 

 tendency to malformation." Darwin adds, furthermore: ''That 

 any evil directly follows from the closest interbreeding has been 

 denied by many persons, but rarely by any practical breeder 

 and never, as far as I know, by one who has largely bred ani- 

 mals which propagate their kind quickly." 



On account of the almost universal prejudice against inbreed- 

 ing, or because the results of former work seemed conclusive, the 

 problem of inbreeding was practically ignored by scientists 

 after the publication of Retzima-Bos' results in 1893, and only 

 within the past decade has it again received any serious consid- 

 eration. The recent experiments of Gentry ('05) on swine, of 

 Castle et al. ('06) and of Moenkhaus ('11) on Drosophila, and 



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THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 26, NO. 1 

 MAY, 1918 



