Sept. 18,1916 Dwarf Eggs 1029 



between the two parts, and thin albumen surrounded both thick albumen 

 envelopes, which were distinct. In both cases the dwarf egg was at the 

 pointed end and the normal egg at the blunt, or air-cell, end. In both 

 cases the membrane of the yolk in the normal egg was uninjured. In 

 neither case was there any yolk in the dwarf egg. The only visible 

 nucleus in each case was a mass of chalaza-like coagulated albumen fibers. 

 In -these cases also the dwarf egg seems to have preceded the normal egg 

 down the oviduct. The normal egg apparently overtook the dwarf egg 

 at the end of the albumen-secreting portion of the duct. The origin of 

 the coagulation fibers, which apparently furnish the stimulus for the 

 formation of the dwarf egg in these cases, is not known. 



In one case the compound egg was produced by a pullet one month 

 after she began to lay. During this month the bird had produced nine 

 eggs and nested without laying on eight days. The bird nested without 

 laying on the first, third, fourth, and fifth days before the abnormal egg 

 was produced. The day following the abnormal egg she neither nested 

 nor laid. On the next two days she laid normal eggs. From this time 

 on the number of nesting records decreased and the number of eggs in- 

 creased. This is the only abnormal egg ever produced by this bird. She 

 continued to lay well until sold at the end of her pullet year. 



In the other case the bird was about a year old. At the time the egg 

 was produced she had been laying steadily for a month and a half. All 

 the eggs had been normal. The bird had not laid on the day preceding 

 the production of the compound egg. On the following day she pro- 

 duced a dwarf egg which contained a mass of chalaza-like coagulated 

 albumen fibers, but no yolk. These two abnormal eggs were the first 

 eggs in a clutch of five, the three others of which were normal. The bird 

 continued to lay for 4^ months — that is, until the end of August — never 

 again producing an abnormal egg. She was sold one week after she 

 stopped laying. 



b. — DOUBLE EGGS IN WHICH THE INCLOSED EGG, AND SOMETIMES ALSO THE INCLOS- 

 ING EGG, WAS DWARF 



A dwarf egg is sometimes inclosed within a normal egg, or may furnish 

 the nucleus of a larger dwarf egg (10). The cases of this kind which have 

 occurred at the Station plant will in the near future be described in con- 

 nection with a discussion of double or inclosed eggs. So far as possible, 

 the description of cases will be left to a future paper. It seems necessary 

 to summarize them here. A dwarf egg may be returned up the duct and 

 meeting a normal egg may be included with it in a common set of egg 

 envelopes. Of more interest to the present investigation are the cases 

 where a dwarf egg is inclosed in a larger dwarf egg. 



One case where such an egg was produced by a bird with a constricted 

 ring of tissue in the upper oviduct has already been cited. This egg was 

 the first of a series of three dwarf eggs. (See Table XXVIII.) The 



