SINGLE-COMB MINORCA AND WHITE-CRESTED POLISH. 



This table gives the distribution of characteristics in 70 individuals. 

 Grouping the individuals under certain alternative characters, we have the 

 following relations of actual and calculated frequency of occurrence of each 

 characteristic : 



The actual never deviates far from the expected. 



If, however, we compare the actual number of cases of each of the combi- 

 nations with the calculated the result is instructive. For example, in the 

 absence of correlation of characters we should expect a high nostril to be 

 associated with a single comb in 5 or 6 of the 22 cases ; but it is never found so 

 associated. In fact a high nostril never occurs in this cross dissociated Jrom a 

 rudimentary comb. On the other hand, it appears that a low nostril may be 

 associated with a rudimentary comb, but in unexpectedly few cases, 4 instead 

 of about 14. Two of the 4 records are from embryos in the shell, in which 

 therefore adult characteristics were not fully developed and the other two 

 cases are recorded as one-half high. It is quite possible that an atypical 

 nostril and absence of true comb are always associated (fig. u). 



In order not to complicate the table too much, the correlation between 

 crest and color of the crest feathers was omitted. A subsidiary table is con- 

 sequently given here : 



Crest present. 

 Crest absent . 



f Black 18 



\ White and black 23 



/Black 9 



' ' \ White and black 6 



56 



Whether crest is present or absent white occurs on the head ; but it is more 

 apt than not to occur when the crest is present and less apt than not when 

 the crest is absent. 



CONCLUSIONS. 



In the cross under consideration no characteristic is inherited in strictly 

 Mendelian fashion, for in no case is dominance complete. The nearest ap- 

 proach to typical Mendelian dominance is exhibitedTin the present cross, only 

 when crest is crossed with no crest. The new additive characteristic crest 



