294 J- T - PATTERSON. 



have been studied in detail, with the result that a number of 

 interesting facts concerning the sexes have been brought to light. 

 Of the hundred and twenty-nine broods, three are pure female 

 broods, sixteen pure male, and one hundred and ten mixed. 

 The three female broods have 1,089, 1.306, and 1,859 indi- 

 viduals, respectively; while the sixteen male broods run as 

 follows: 385, 432, 525, 578, 675, 699, 988, 1,003, 1.124, 1,277. 

 1,285, 1,288, 1,333, 1,354, I >492, 1,588. This is an average of 

 1,001 individuals per brood. 



It is the mixed broods which are of special interest. The 

 number of individuals in these broods varies from 545 to 2,028, 

 with an average of 1,246 individuals per brood. The percentage 

 of males varies from 72.07 to .06. In Table II. are listed sixty 

 broods, in which the sex of each individual has been carefully 

 determined. These are arranged in the order of per cent, of 

 males, from the highest to the lowest. Fifty additional broods 

 are listed in Table III., in which the total number of individuals 

 is given, and the per cent, of males as determined by a study of 

 five hundred individuals in each brood. This method of study- 

 ing the sexes does not give the exact number of males and females 

 in a brood, but it yields a very close approximation to the true 

 per cent, of males. 



These data raise a number of interesting points, only a few of 

 which can be considered here. One of the most striking features 

 is the scarcity of pure broods. Of all the broods studied, only 

 about twelve per cent, are male broods, and less than three per 

 cent, female broods. Another equally striking feature is the 

 great preponderence of females in the mixed broods. In only 

 seven of the one hundred and ten such broods is the number of 

 males in excess of the number of females (broods I, 2, 3, 4, 5, 6, 

 61, Tables II., III.). In the remaining one hundred and three 

 cases the females are in the majority. 



Reference to Tables II. and III. will show that in over 58 per 

 cent, of the broods less than ten per cent, of the individuals in 

 any given brood are males, while in 35 per cent, of the cases 

 there is less than three per cent, of males. The most striking 

 cases are those listed toward the bottom of the tables, especially 

 the last six or seven broods in each table. In each of the last 



