264 POULTRY CULTURE 



unfavorable condition or irregularity during incubation, it is espe- 

 cially important to note carefully the amount of deviation from the 

 normal condition or from approved practice. As a rule, occasional 

 or moderate variation from prescribed conditions will not materially 

 affect results, although a wider deviation, or too many slightly un- 

 favorable conditions occurring simultaneously, might cause a poor 

 hatch. On this account any noticeable variation from conditions 

 which it is designed to maintain throughout the period of incu- 

 bation must be regarded as a possible cause of an unsatisfactory 

 hatch, and must further be considered a possible cause of mortality 

 in the young birds, and perhaps of lack of vitality in those that 

 survive to maturity. 



Causes of poor hatches. The causes of poor hatches have been 

 indicated in preceding paragraphs, but it is worth while to summarize 

 them here and to comment on some points. A fertile egg with 

 germs of normal vitality, when incubated naturally, will (barring 

 accident) produce in due time a vigorous bird. Failure to do so 

 indicates lack of fertility or vitality, or is evidence of neglect or 

 accident. It cannot be assumed that, with all conditions and factors 

 right, the failure of the embryo to develop is normal. It must be 

 assumed that, if all the facts were known, the cause of a poor hatch 

 in any case would be plainly apparent. It is not always possible to 

 know all the facts, yet in a majority of cases the known facts show 

 causes sufficient to account for the results, as will appear if the 

 operator, instead of making mental comparisons, will write down 

 systematically the conditions of a good hatch, and opposite each 

 item note the condition in the hatch under consideration. 



The general causes of poor hatches are (I) poor eggs and (2) 

 wrong management. For the quality of the eggs the responsibility 

 is with the breeder or, where all operations are in the same hands, 

 is to be considered in connection with the subject of breeding. The 

 determination of the hatching quality of the eggs is a necessary 

 preliminary to consideration of the conditions of incubation. In by 

 far the greater number of cases of poor hatches with incubators, 

 the quality of the eggs is unknown, the operator having no check 

 of any kind on his results. In such cases he is all at sea, and any 

 consideration of how points in management may have affected 

 results is mere speculation, except when it is known that some 



