DISEASES OF POULTRY. 157 



shell has been deposited. 'Eggs without shells are 

 more difficult to lay than are those which are perfect, 

 and, hence, they are frequently retained a considerable 

 time in the uterus, adding to the irritation and inflam- 

 mation. As treatment in these cases, it is sufficient 

 to remove the cause. Give the fowls plenty of shell - 

 forming material such as wheat bran, crushed egg 

 shells, cut or calcined bone, broken mortar, crushed 

 oyster shells, etc. Give green food and avoid the 

 causes of inflammation of the oviduct. 



EGGS WITH TWO VOLKS. 



Eggs are frequently found in which there are two 

 yolks, and these are popularly known as double - 

 yolk eggs. They are the result of two ovarian cap- 

 sules becoming ruptured at about the same time, and 

 the yolks descending the oviduct so near together that 

 both are included in the same shell. Eggs with two 

 yolks are generally larger than others, and there is 

 more danger that they will cause injury to the oviduct. 

 Some hens are habitual layers of such eggs. If incu- 

 bated, double -yolk eggs generally produce twins, 

 double chicks, or monsters. All such abnormalities are 

 not developed from these eggs, however, as it has been 

 shown by Davaine that a single yolk may contain two 

 germs and give birth to two embryos united in some 

 part of the body. 



INCOMPLETE OR ABORTED EGGS. 



It is common for hens to drop eggs of only half or a 

 third the diameter of those usually produced. These 

 diminutive productions, often about the size of a 

 pigeon's egg, are provided with a shell sometimes more 

 dense than that of the normal egg. On examination 

 they are found to contain albumen but no yolk. In 

 some cases they contain little l)ut the albumenous 



