1016 Journal of Agricultural Research vol. vi.no. 2S 



occasion anxiety. They usually occur at or near the end of a batch of 

 eggs and merely show that the ovary is exhausting its supply of ova or 

 yolks a little before the secreting parts of the oviduct are quite ready to 

 suspend business." Lewis (8) explains dwarf -egg production, which 

 he says is common at the beginning or end of a laying period, as "in part 

 due to a diminution in the size, hence in the lessened secreting power of 

 the oviduct." These views are untenable in the face of the facts cited 

 above. Bonnet (2) says that such eggs mostly arise through pathological 

 processes in the oviduct. 



On the basis of unpublished data, Pearl, Surface, and Curtis (21, p. 176) 

 made a statement of the factors which were probably involved in dwarf-egg 

 production. The data on which this statement was based are included 

 in the data used in the present investigations. The data then on hand 

 indicated that three fundamental factors are concerned in dwarf-egg 

 production. These are: 



1 . The bird must be in an active laying condition; the more pronounced the degree 

 of physiological activity of the oviduct the more likely are these eggs to be produced. 



2. There must be some foreign body, however minute, to serve as the stimulus 

 which shall start the albumen glands secreting. This foreign body may be either 

 a minute piece of hardened albumen, a bit of coagulated blood, a small piece of yolk 

 which has escaped from a ruptured yolk, etc. 



3. It seems likely, though this is a point not yet definitely settled, that ovulation — 

 that is, the separation of a yolk from the ovary — must precede the secretion of albumen 

 around the foreign body to form one of these eggs. 



To a large extent the complete investigation confirms and extends 

 these conclusions. The data which contribute to our knowledge of the 

 physiology of dwarf -egg production are the complete egg records and the 

 autopsy records of dwarf-egg producers. 



A. — EVIDENCE FROM THE EGG RECORDS AND AUTOPSY RECORDS OF DWARF- 

 EGG PRODUCERS WITH ABNORMAL SEX ORGANS 



It has already been noted that the egg records for 1 1 of the 200 known 

 dwarf -egg producers showed that few or no normal eggs were produced 

 after the dwarf egg or eggs. Such birds usually make nesting records, 

 the dwarf egg occurring in a series of the nesting records. As an illus- 

 tration, the egg record of case 1 is given in Table XXVIII. 



From this record it may be seen that the bird was a heavy layer, pro- 

 ducing 162 eggs up to May 28. After this she produced only one normal 

 egg (on June 26). The nesting records occurring in clutches indicate that 

 the ovary passed through its normal cycles. Four dwarf eggs were pro- 

 duced in a series of nesting records. The bird made her last nesting 

 record on January 16. Twenty-four days later (February 9) she was 

 killed for data. She was in a normal healthy condition and was very fat. 

 The visceral organs were apparently all perfectly normal, except the 

 oviduct. The ovary contained an enlarging series of yellow yolks, four 



