828 



SCIENCE 



[N. S. Vol. XXXIX. No. 1014 



remarks that lie is not in agreement with 

 Guyer in regard to the accessory. Guyer refers 

 to this matter as only a " slight discrepancy " 

 but to my own way of thinking, it is the only 

 evidence (in default of better evidence, un- 

 fortunately) on which we can at present judge 

 concerning the nature of these bodies that 

 Guyer identifies as the sex chromosomes. Irre- 

 spective, therefore, of whether Guyer is right 

 or wrong, it still seems to me that Mont- 

 gomery's statements can not properly be said 

 to be like those of Guyer except for a " slight 

 discrepancy." 



It may he invidious to point out here that 

 the kind of evidence that Guyer admits in 

 favor of the two chromosomes in man being 

 sex chromosomes is of the same sort as the 

 evidence that he has brought forward for 

 similar bodies in birds. The recent thorough- 

 going analysis of Pearl and Boring has made 

 apparent that this kind of evidence is in itself 

 inconclusive and unconvincing. The experi- 

 mental evidence indicates very strongly that 

 in birds the female is heterozygous for a sex 

 factor. 



There is another and not unimportant differ- 

 ence between Guyer and Montgomery. Guyer 

 states that a second pairing of the ordinary 

 chromosomes takes place in man. Mont- 

 gomery says : 



I have seen no evidence of any kind of such a 

 pairing of chromosomes in the secondary sperma- 

 tocytes, neither in my own material nor in that 

 received from Guyer, though I have examined fully 

 two himdred division stages of these cases. 



While the second point does not bear directly 

 on the " disagreement " in regard to the sex 

 chromosomes, it raises a doubt as to the value 

 of material that can lead to such diametrically 

 opposed results, for the conflicting statements 

 relate to the same identical preparations. 



In order that no misunderstanding may 

 arise I may add that I am entirely in sympathy 

 with the view that in the human race the male 

 is heterozygous in a sex factor ; for the experi- 

 mental evidence relating to sex-linked inher- 

 itance strongly indicates that this is the case. 



It is with great interest I note in the last 

 paragraph of Guyer's paper a hint (or is it 



intended as an announcement?) that the white 

 man has more chromosomes than the negro — 

 a point of view I mentioned^ in the book under 

 discussion as a possible way of harmonizing 

 Guyer's results with those of v. Winiwarter. If 

 the suggestion is established, some revision 

 may be necessary concerning the Mendelian 

 expectation for the inheritance of skin color 

 in the black-white cross. 



T. H. Morgan 



SCIENTIFIC BOOKS 



INTRODUCTION TO THE NEW STATISTICS WITH 



SPECIAL REFERENCE TO THE NEEDS OP 



BIOLOGISTS 



The number of guides to modem statistical 

 methods consequent upon the realization that 

 mathematical analysis is necessary for the full 

 interpretation of series of observations is now 

 so large that it may be helpful to the beginner 

 to point out some of their chief features. 



While Francis Galton's " Hereditary Gen- 

 ius " of 1869 shows the influence of the work 

 of Quetelet, his " Natural Inheritance " of 

 1889 is probably the first book published in 

 which the modem student can find any con- 

 sistent comprehensive explanation of the sta- 

 tistical methods as applied to biological prob- 

 lems. While this classic should be familiar 

 to every statistician, it is not suitable as a 

 guide to the beginner, for the formula there 

 described have been replaced by those better 

 suited to the practical routine of calculation. 



Among the earlier treatises on the new sta- 

 tistics — speaking now of introductions and 

 guides, not of original work — may be men- 

 tioned those of Duncker^ and Davenport^ 

 written from the standpoint of methods and 

 the volume of Vernon^ prepared more as a 



1 First suggested in 1912 by Gutherz but re- 

 jected by him. 



1 Duncker, G., ' ' Die Methode der Variations- 

 statistik, " ArcMv. f. EntwicMungsmechaniJc d. 

 Organismen, Vol. VIII., pp. 112-183, 1899. 



2 Davenport, C. B., ' ' Statistical Methods with 

 Special Reference to Biological Variation," New 

 York, 1899, second ed., 1909. 



3 Vernon, H. M., ' ' Variation in Animals and 

 Plants," New York, 1903. 



