UNISEXUAL TENDENCY 11 



parents to produce female children. It is this conihined tendency toward 

 the production of children of one sex in some cases and the other sex in 

 other cases that, for the present purpose, I term unisexual. 



The data for the investigation in question have been derived from two 

 sources. Mr. Hunt, chief of the Division of Population Statistics in 

 the Census Office, very courteously made for me a count of 2000 families 

 in which the parents were of various nationalities, enumerated in the 

 census of 1900. I have also had counts made from a genealogy includ- 

 ing all the known families descended from one Andrew Kewcomb, who 

 died about the year 1650, and which served a valuable purpose as prob- 

 ably including a wider range of conditions than those affecting the fami- 

 lies enumerated in the. Census. This was further extended to include 

 great number of other family genealogies. The entire list may there- 

 fore be taken to include the widest possible range of ordinary conditions 

 which might affect the sex of offspring. 



In the following summary of families, the first column of figures 

 gives numbers for the white families as supplied by the Census Office. 

 The second gives the corresponding numbers for families taken from 

 the genealogies. The third and fourth columns give the data for the 

 negro and Indian families, as supplied by the Census. The fifth gives 

 the sum for all the families. 



This is followed by the probable numbers given by the theory of 

 chances, in case that there is no unisexual tendency among parents. 



In each column the first line is the total number of families, the 

 second the number of those families of which the children are all of 

 the same sex, whether male or female. The following lines give the 

 number of bisexual families of each class, each division of the number 

 between the two classes being combined. For example, in families of 

 4 children, the line marked 3 and 1 gives the combined number of fami- 

 lies comprising 3 males and 1 female, together with those comprising 

 1 male and 3 females. The totality of the families enumerated is too 

 small to give any value to the separate enumeration of males and females. 

 A combination is therefore made in order to reduce the results to the 

 smallest number of distinct data. Thus the reader can see at a glance 

 to what extent, if any, a bisexual tendency can be found in the fami- 



lies enumerated. 



FAMILIES OF 2 CHILDREN. 



Class 8 G gy Negro Indian Total Probable 



Number of families ........ 670 1051 56 6 1783 



Same sex 322 547 30 2 901 892 



Opposite sexes 348 504 26 4 882 892 



