556 Journal of Agricultural Research voi. xii, no. 9 



As inspection of these records shows that there are pronounced family 

 resemblances in the number and length of pauses among the members of 

 each of several families, and since environmental influences have been 

 excluded, as far as possible, it is evident that our material is not homoge- 

 neous from the biometrical standpoint. Consequently most of the usual 

 biometrical constants have not been calculated, since in this case such 

 constants tend to conceal the differences we are endeavoring to find. 



MEANS BY WHICH A WINTER CYCLE MAY BE RECOGNIZED 



A. — PAUSES 



LENGTH AND SEASONAL DISTRIBUTION 



Two questions arise in regard to the length of the pauses: First, is 

 there any significant difference in the length of pauses? Second, is there 

 any difference in the distribution of pauses of varying length through the 

 winter? Table II shows the percentage distribution of pauses beginning 

 at two days in length, grouped according to the month of origin. The 

 combined values for the three years are shown in the last column. It 

 is clear that the pauses fall into two classes, short and long, the dividing 

 line between the two groups falling at about 10 days. Further, it is 

 evident from the table that the long pauses originate mainly in December 

 and January, and to a less extent in February, but that the short pauses 

 are distributed in a fairly uniform manner throughout the winter.^ An 

 examination of the pauses occurring in March and April not due to 

 broodiness shows that while all pauses are less numerous than in the 

 winter, and while a few long pauses may be found, most are short ones 

 occurring in practically the same proportions observed in the other 

 months. 



' The increase in long pauses originating in December and January automatically decreases the percent- 

 age of the short pauses so that relatively they are somewhat less numerous in spite of the percentages 

 being about equal. 



