STUDIES ON THE PHYSIOLOGY OF REPRODUC- 

 TION IN THE DOMESTIC FOWL. 



III. A CASE OF INCOMPLETE 



RAYMOND PEARL AND MAYNIE R. CURTIS 



ORIGIN AND GENERAL CHARACTER OF SPECIMEN. 



From a chick hatched in the spring of 1907, at the Maine 

 Agricultural Experiment Station, there developed the bird 

 which forms the subject of this paper. This bird was a Barred 

 Plymouth Rock and when adult presented externally the general 

 appearance of a normal hen of this variety, so far as the charac- 

 ters body form and plumage color were concerned (cf. Plate I.). 

 As the photograph in Plate I. shows, however, the head and 

 neck resembled these parts in a cockerel. This resemblance was 

 especially remarkable in respect to the size and shape of the 

 comb and wattles. The comb was obviously much larger than 

 the comb of a normal Barred Plymouth Rock hen and looked 

 exactly like the comb of a male bird. This was also true of the 

 wattles. 



The dimensions 2 of the comb of this bird were as follows : 



Length ........................................................... 88.4 mm. 



Calculated height .............................................. 25.1 mm. 



Area ............................................................... 22.2 cm. 2 



For normal adult Barred Plymouth Rock females the follow- 

 ing average values for comb size have been found : 3 



Mean length ............................................ 50.80 .56 mm. 



" calculated height ............................. 10.57^.23 " 



" area ............................................. 5.59 .!7cm. 2 



It is evident from these figures that the comb in this specimen 

 greatly exceeds in size the average for females of the variety. 



1 Papers from the Biological Laboratory of the Maine Agricultural Experiment 

 Station, No. 13. 



2 Made in accordance with the methods described by R. and M. D. Pearl in a 

 paper "Data on Variation in the Comb of the Domestic Fowl," Biotnctrika, Vol. 

 VI., pp. 421-423. 



3 Pearl, R. and M. D., loc. cit., p. 427. 



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