INHERITANCE OF WINTER EGG PRODUCTION 123 



covered until 1915. Later, when the agglutination test was 

 applied to all breeders, reactors belonging to the original flock 

 were found. Thus most of the mortality during the first three 

 weeks after hatching in 1913, 1914, and 1915 must have been 

 due to this disease, as no difficulty is experienced at present in 

 rearing chicks. During and since 1915, the experimental flocks 

 have been free from this trouble. 



b. Filth diseases. There is a group of diseases about which 

 very little is known, but which we infer are spread by filth. It 

 has been the common practice for years to clean and disinfect 

 brooders or colony houses, place baby chicks therein, take pains 

 to clean the brooders frequently while the chicks are growing, 

 but no attention is paid to the ground over which the chicks 

 run, which may be the adjoining hen yard, nor does the attend- 

 ant make the slightest effort to avoid the transfer of filth from 

 the adult birds, especially by means of his feet. If, however, 

 adequate measures are taken to prevent such contagion, trouble 

 from this source disappears. In addition to bacillary white 

 diarrhea, trouble from this class of diseases was experienced in 

 1913 and 1914, and in that part of the flock of 1915 which was 

 not isolated. In 1915, most of the chicks were reared under 

 isolation. In 1916 and 1917, all the chicks were reared on clean 

 ground by a special attendant. 



APPENDIX 2 



Remarks to practical poultrymen 



Theories of egg production are of little interest to the prac- 

 tical man unless they can be turned into actual eggs. The 

 poultryman has been told first one thing and then another about 

 breeding for more eggs until the time is approaching when he 

 will believe that it is all humbug. The situation is, indeed, con- 

 fusing. This is because the various theories that have been and 

 will be developed are necessarily attempts at reducing the 

 available facts to order. They should be regarded as reports of 

 progress and subject to revision. Theories, however, are ex- 

 tremely useful, because they stimulate further investigation 



