94 MASS. EXPERIMENT STATION BULLETIN 199. 



the Asiatics, i.e., Langshans, Cochins and Brahmas, may be cited as 

 examples of the former, while Hamburgs and Campines, and the Mediter- 

 ranean breeds, i.e., Leghorns, Spanish and Anconas, furnish examples 

 of the latter. The distinction is based on the proportion between broody 

 and non-broody individuals in each race, for some non-broody individuals 

 occur among the broody races, while records are lacking to show that 

 broody individuals are entirely absent from any of the non-broody races. 

 The Leghorns are commonly regarded as a non-broody race, but as shown 

 in Table VI, taken from the report of the fifth laying contest at Storrs 

 (Kirkpatrick and Card, 1917), a considerable number become broody. 

 It is a matter of coriimon knowledge among poultry keepers that among 

 the broody races there are considerable differences, some races, of which 

 the Rhode Island Reds are an example, having an intense development of 

 broodiness compared with others, such as the Barred Plymouth Rocks, 

 in which the amount of broodiness is relatively slight. 



There are few published reports on the character in the domestic fowl, 

 though there is, of course, a considerable amount of matter scattered 

 through the poultry literature, in which broodiness is mentioned in a 

 more or less general way, but which is of no importance from the stand- 

 point of this paper. Both Bateson's (1902) and Hurst's (1905) data showed 

 that in a cross between a broodj^ and non-broody race, broodiness was 

 dominant, but they have published no further observations. Pearl (1914) 

 has published certain data relating to broodiness, with which in general 

 our data agree. A repetition of the same sort of material is unnecessary 

 here. His methods of collecting the data and of handling the broody 

 birds also are essentially the same as our practices in these respects. In 

 general, our experience with this instinct agrees with his, except that 

 there are two points for which different interpretations may be presented. 

 On page 285 {he. cit.) he makes this statement: "It appears to be the 

 case that in the domestic fowl the brooding instinct has to a very large 

 degree disappeared along with the fact of domestication." Evidently 

 this author had not encountered a strain like our Rhode Island Reds, for 

 such a statement would be impossible after an experience with such a 

 strain. In the second place, we entertain some doubt as to the advis- 

 ability of measuring the intensity of broodiness by the length of the non- 

 productive period associated with the objective symptoms of broodiness 

 {loc. cit., page 273), because, while the cessation of egg production coin- 

 cides in nearly every instance with the onset of objective symptoms, the 

 resumption of production is often delayed by other factors, among which 

 may be noted the innate capacity for egg production and readiness to 

 molt. In regard to its effect on egg production, Goodale (1918) makes 

 the statement that the ratio between the egg production prior to the 

 first broody period and that subsequent thereto is about 100 :60. ^ Gerhartz 

 (1914) has studied the metabolism of the broody hen in connection with 

 his studies on the metabolism of the laying hen. 



1 The data on which this statement is based are given for the first time in Table VIII. 



