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THE AMERICAN NATURALIST [Vol. XLIII 



with the moth Abraxas. It is hoped Professor Wilson may be 

 able to make cytological studies on some of these cases. 



The fact that such characters as eye color in canaries, barring 

 in poultry, and melanic types in Abraxas may be coupled with 

 sex points strongly to the chromosomic nature of these char- 

 acters. The work of Professor R. R. Gates, and that of Miss 

 Annie E. Lutz on the chromosomes of CEnothera points strongly 

 to the assumption that chromosomes are the elements with which 

 we have to deal in the study of hereditary characters. Their re- 

 sults indicate that mutations of the De Vriesian type are due to 

 accidents in mitosis. Miss Lutz remarks: 5 



The numbers of chromosomes are closely associated with external 

 characters in the lirst and Inst, and prohably also in the second group. 



Professor Gates has also expressed the opinion that abnormal 

 chromosome behavior may account for the mutation phenomena 

 observed by De Vries. It seems probable, therefore, . that muta- 

 tions of this character do not represent what we may call normal 

 evolutionary changes, but that the latter must be sought in 

 changes in the chemical constitution of the chromosomes. 



W. J. Spillman. 



ENVIRONMENT 



The Effect of Environment upon Animals "Katy-did, Katy- 



didn't" seems to continue to be a fair summary of the situation 

 with respect to the heredity of acquired characters and the part 

 played by environment in evolution. Wallace wrote in the 

 Fortnightly Review (January, 1908) restating his belief in 

 natural selection and recommending a careful study of Reid's 

 "The Principles of Heredity" and Ball's "Are the Effects of 

 Use and Disuse Inherited?" Rev. Henslow followed his advice 

 and has published a short, suggestive and very readable book 1 

 on "The Heredity of Acquired Characters in Plants," in which 

 he states with even more assurance than before the conclusion 

 of his "Origin of Plant Structures," that "the Origin of Species 

 is due to the joint action alone of the two great factors of evolu- 

 tion— Variab'lit >/ and En viron ment — without the aid of natural 

 selection." This additional assurance seems to be the result of 

 the growth of the ecological school of botanists and his belief that 

 ecologists are "all at one" in accepting the fact that evolution 

 in plants is the result of the effects of the environment which can 

 become heredity. 



1 London, John Murray, 1908, 107 pp. 



