920 



SCIENCE 



[N. S. Vol. XXVII. No. 702 



The impression made by this general 

 examination of the present bird popula- 

 tion of the state of Illinois was that of a 

 remarkable flexibility and tenacity of the 

 associate and ecological relationships of 

 birds in the face of revolutionary changes 

 in their environment. Apart from the re- 

 sults of the introduction of the English 

 sparrow, and the direct destruction of 

 game birds and birds of prey, the main 

 effect of human occupation seems to have 

 been the withdrawal of most of the prairie 

 birds from the area devoted to Indian 

 corn, and their concentration in pastures, 

 meadows, and fields of small grain— situa- 

 tions which most nearly resemble their 

 original habitat. 



Significant Changes in the Breeding 

 Ranges of Certain Birds of the Ohio 

 Valley and Lower Lake Region: Ltnds 

 Jones, Oberlin College. 

 These changes, during a period of 

 seventy years, are a gradual but decided 

 shifting northward of the breeding areas of 

 twenty-five species of birds, or fully 

 twenty per cent, of the breeding birds of 

 the state of Ohio. The movement can not 

 be accounted for by the changes attendant 

 upon the settlement of the region, because 

 the breeding habitats have not been ma- 

 terially changed. Eather the northward 

 movement seems to be the expression of a 

 gradual elimination of the less fit and as 

 gradual an improvement of the species. 



The Relation of Ecology to General Bio- 

 logical Problems: A sjrmposium by H. C. 

 CowLES, V. E. Shelpobd, C. C. Adams, 

 the University of Chicago. To be pub- 

 lished in full in Science. 



A Study in the Sex-ratio in Brosophila 

 Ampelophila: W. J. Moenkhaus, Uni- 

 versity of Indiana. 

 The sex-ratio in Drosophila ampelophila 



is 1 male to 1.14 females. The sex-ratio is 

 inherited. If the sex-ratio of many pairs 



of this species taken from the same parents 

 as determined in different pairs shows a 

 wide range of variation in this respect. 

 The ratio may vary from a slight pre- 

 ponderance of males to a strong preponder- 

 ance of females in a proportion of 1 to 2 

 or greater. By breeding the offspring 

 from pairs showing a selected ratio, these 

 again show a ratio approaching that of 

 their parents. Thus, by selection, a strain 

 in which the females bore a relation 1.6 to 

 1 male was produced. This ratio, by selec- 

 tion, can be maintained. A male strain 

 has not yet been attempted. 



By mating females from the "female" 

 strain with males from a strain in which 

 the sex-ratio is 1 to 1, and vice versa, the 

 sex-ratio of the offspring is in every case 

 that of the strain from which the females 

 were selected. Prom the results in five 

 such experiments it is concluded that in 

 this creature the sex is determined alto- 

 gether, or nearly so, by the female, the 

 male having nothing or little to do with it. 

 The objection that might easily be 

 brought forward, that the selection in these 

 experiments may be nothing more than the 

 selection of those pairs in which one sex or 

 the other tended to die and, hence, led to 

 a preponderance of one sex or the other, 

 has not been met satisfactorily experi- 

 mentally, but it is not regarded as a factor 

 of any importance. 



Thomas G. Lee, 



Secretary 

 Univebsity of Minnesota 



{To be concluded) 



SCIENTIFIC BOOKS 



SCIENTIFIC PUBLICATIONS OF THE AMERICAN 

 MUSEUM OF NATURAL HISTORY FOR 1907 



In Volume XXIII. of the Bulletin of the 

 museum there are almost one thousand — 978, 

 to be exact — printed pages, comprising thirty- 

 six separate papers from nineteen authors, 

 with fifty-three plates and eighty-three text 

 figures. Many papers are of typical tech- 



