Sept. 18. 1916 Dwarf Eggs io 39 



(16) It is probable that the variation in yolk weight compared to the 

 variation in the other egg parts and to the whole egg is greater in dwarf 

 eggs with small yolks than in normal eggs. 



(17) The interrelation of the size and shape characters in prolate- 

 spheroidal f dwarf eggs of each class is as follows : 



a. Length and breadth, length and weight, and breadth and weight 



are significantly highly correlated in eggs of each group. 



b. Index and weight are negatively correlated. The correlation is 



significant for dwarf eggs with little or no yolk. 



c. In dwarf eggs with small yolks, yolk weight is highly correlated 



both with egg weight and with albumen weight. 

 The physiological significance of these correlations is discussed. 



(18) During the last eight years 5.15 per cent of all the birds kept at 

 the Maine Station plant are known to have produced at least one dwarf 



egg- 



(19) Both the actual dwarf -egg production and the number of dwarf 

 eggs per 1,000 eggs is lowest during the winter months. It increases 

 through the spring, reaching a maximum in the early summer. 



(20) In general the season of high normal-egg production is also the 

 season for high dwarf-egg production both actual and relative to normal- 

 egg production. The maximum of dwarf-egg production, however, oc- 

 curs later in the season than the maximum normal-egg production. 



(21) The production of a dwarf egg is usually an isolated phenomenon 

 occurring only once or twice, during the life of a bird. Only 3.5 per 

 cent of the birds which produced one or more dwarf eggs produced more 

 than two. 



(22) A study of all the egg records and the available autopsy records 

 for birds which produced one or more dwarf eggs shows that in most 

 cases the disturbance which caused the production of the dwarf egg was 

 of temporary character and was not correlated with a morphological 

 disturbance of the sex organs. 



(23) Eleven of the two hundred dwarf -egg producers, however, showed 

 evidence that a permanent disturbance had occurred. In these cases 

 few or no normal eggs were produced after the dwarf egg or eggs, although 

 nesting records indicate that the ovary passed through normal repro- 

 ductive cycles. 



(24) Autopsies were made on five of these cases, and all of them 

 showed some pathological condition of the oviduct which interfered with 

 the passage of the egg, but did not entirely close the duct. 



(25) In normal birds dwarf-egg production is most likely to occur 

 during the height of the breeding season. It is not associated with 

 immaturity of the sex organs. 



1 The same relations apparently also hold for cylindrical dwarf eggs, but the number observed was too 

 small to determine the degree ol relationship. 



55853°— 16 5 



