JOURNAL OF AGMLTO RESEARCH 



DEPARTMENT OF AGRICULTURE 



Vol. VI Washington, D. C, September 18, 1916 No. 25 



STUDIES ON THE PHYSIOLOGY OF REPRODUCTION 

 IN THE DOMESTIC FOWL.— XV. DWARF EGGS 1 



By Raymond Pearl, Biologist, and MayniE R. Curtis, Assistant Biologist, 

 Maine Agricultural Experiment Station 



INTRODUCTION 



Eggs much smaller than normal eggs are occasionally produced by 

 domestic fowls of all breeds. These eggs usually contain little or no yolk ; 

 but occasionally a small yolk, usually without germ disk but inclosed in 

 a complete vitelline membrane, is present. The albumen is small in 

 amount, and often but not always it is of a thicker consistency than the 

 albumen of a normal egg. The egg membranes are normal. The shell 

 varies in thickness over the same range as the shells of normal eggs. 

 Sometimes, as in eggs otherwise normal, shell is entirely lacking — that is, 

 the egg is simply covered with a membrane. 



These small eggs are called by various names as "cock eggs," "witch 

 eggs," "luck eggs," "wind eggs," "dwarf eggs," etc. Most of these 

 names are associated with interesting superstitions. The term used by 

 the people in any particular part of the world depends in part on the 

 folklore of the region. Since no single term is generally accepted, we 

 have decided to use a name which, although it has no legendary history, 

 is somewhat descriptive. We have therefore called these small eggs 

 "dwarf eggs." 



Among the various types of abnormal eggs produced by the domestic 

 fowl the dwarf egg is more common than any other type except the double- 

 yolked egg. This type of egg has played an important role in the folk- 

 lore of all nations. Sebillot (2 2), 2 Tiedeman (25), Konig-Warthausen (7), 

 and Bonnet (2) give some of the popular superstitions connected 

 with these eggs. A widespread superstition which comes down nearly 

 to our own time is that a cock, or especially a very old cock, produces 

 these eggs. These "cock" eggs were sometimes supposed to be made up 

 of semen and "humors." A superstition which was quite widely ac- 

 cepted at an early period was that such an egg might hatch into a fabled 



1 Papers from the Biological Laboratory of the Maine Agricultural Experiment Station, No. 98. 



2 Reference is made by numbers to "Literature cited," p. 1041. 



Journal of Agricultural Research, Vol. VI, No. 35 



Dept. of Agriculture, Washington, D. C. Sept. 18, 1916 



fl Maine— 8 



(977) 



