DWARF EGGS OF DOMESTIC FOWL. 293 



178, or 64.96 per cent, contained yolk. Of these, 151, or 55.11 

 per cent, of all the dwarf eggs opened contained yolk not 

 enclosed in a yolk membrane. A small yolk was present in 

 27, or 9.85 per cent, of the dwarf eggs. From these figures 

 it is seen that nearly two-thirds of the dwarf eggs contain yolk. 



II. The Albumen and Shell of Dwarf Eggs. 



We have seen that dwarf eggs differ in respect to the 

 nucleus around which the albumen is formed. Bonnet 3 states 

 that the nature of the albumen is also generally altered. The 

 dwarf eggs observed differed greatly in respect to the density 

 of the albumen. In many it was very condensed, being a thick 

 clear mass which nearly maintained its shape when removed 

 from the shell and egg membranes. It appeared very much 

 like the albumen in a normal egg while it is in the albumen 

 secreting region, or the isthmus of the oviduct. 4 In many 

 other cases it appeared exactly like the albumen of a normal 

 laid egg, that is, there was a somewhat firm inner mass 

 surrounded by a thin fluid albumen. All gradations between 

 these also occurred. In a very few cases the albumen was 

 more fluid than in the average normal egg. There, however, 

 was an undoubted general tendency for the albumen to be more 

 than normally firm. In connection with another investigation 

 in progress at this laboratory the specific gravity of the albu- 

 men of many normal and a few dwarf eggs was determined. 

 The specific gravities of the dwarf eggs ranged widely, with 

 the upper end of the range decidedly above the range for 

 normal eggs. In fact the mean for the dwarf eggs is higher 

 than the maximum for normal eggs, while the minimum for 

 dwarf eggs is only slightly below the mean for normal eggs. 



The egg membranes of dwarf eggs so far as superficial 

 appearance indicates are comparable to those of normal eggs. 

 The shell is sometimes entirely or almost entirely absent as 

 in the case of membrane covered or soft shelled eggs which 



3 Bonnet. 1883. Das Vogelei. Deutsche Zeitschrift fur Thiermedicin. 

 Vol. 9, pp. 239-252. 



4 Pearl, R. and Curtis, M. R. 1912. Studies on the Physiology ot 

 Reproduction in the Domestic Fowl. V. Data Regarding the Physiology 

 of the Oviduct. Jour. Expt. Zool., Vol. 12, pp. 99-132. 



