Sept. 18, 1916 Dwarf Eggs 1007 



bird laid 14 dwarf eggs and no normal eggs. Each of the four others 

 (4.71 per cent) laid two. It is thus apparent that the production of 

 dwarf eggs is not usually an evidence of a permanent abnormality or 

 derangement of the reproductive organs. This view is strengthened by 

 a study of the egg records for the birds which produced dwarf eggs. In 

 almost all cases these birds have a normal egg record. The dwarf egg is 

 preceded and followed by normal eggs quite as though it was a normal 

 egg. Autopsies were performed on several such birds, some immediately 

 after the production of the dwarf egg. The sex organs were morphologic- 

 ally normal. There were, however, 1 1 of the 200 which showed evidence 

 of a permanent disturbance, since few or no normal eggs were produced 

 after the dwarf egg or eggs. In most of these cases the bird made nesting 

 records. It has been shown by the authors (6,13) that "nesting records 

 are, in the great majority of cases, at least, associated with ovulation into 

 the body cavity or the backing into it of partly or fully formed eggs." 

 Furthermore, autopsies were made on 5 of the 1 1 cases and all of these 

 showed pathological conditions of the oviduct which would interfere with 

 the passage of the egg but which did not entirely close the duct. These 

 cases will be discussed in detail later. The point with which we are at 

 present concerned is that the records for only 11 (5.5 per cent) of the 

 200 birds showed evidence of a permanent disturbance of the egg-forming 

 processes. It is then evident that the disturbance which causes the 

 production of a dwarf egg is usually of an accidental or at least tem- 

 porary nature. However, there are certain pathological conditions of 

 the oviduct which result in the formation of a dwarf egg instead of a 

 normal egg. 



The 1 1 cases where dwarf egg production appeared to be related to a 

 permanent disturbance of the physiology of the sex organs include all of 

 cases where the bird produced more than three dwarf eggs, two that pro- 

 duced three, one that produced two, and four that produced only one 

 dwarf egg. The production of a succession of dwarf eggs or of a long 

 series of nesting records with one or two dwarf eggs should lead one to 

 suspect a serious disturbance of the oviduct. 



We will first consider dwarf-egg production which is not associated 

 with a morphological abnormality of the sex organs and will then discuss 

 the pathological cases. 



VIII.— THE RELATION OF DWARF-EGG PRODUCTION BY NORMAL 

 BIRDS TO THE AGE OF THE BIRD AND TO THE POSITION OF THE EGG 

 IN THE LITTER AND CLUTCH 



A. — AGE 



Attention has already been called to the fact that while dwarf eggs may 

 be produced at any season of the year the spring breeding season, the 

 season for highest normal-egg production, is also the season for highest 

 55853°— 16 3 



