3l8 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



a yolk in the egg may have been due to any one of several 

 causes. The three which seem most probable are the following : 



1. A yolk may have been broken during its passage into the 

 duct and only a part of it may have entered the duct. 



2. A part of a yolk ovulated into the body cavity and broken 

 either before or after ovulation may have been picked up by 

 the funnel. 



3. A normal yolk may have entered the duct and being 

 unable to pass the pathological portion may have been broken 

 and a part of it extruded into the body cavity. The remaining 

 portion may have passed the obstruction, becoming the effective 

 stimulus for the formation of the egg envelopes. 



The effective stimulus in the case of the dwarf eggs which do 

 not contain any yolk is difficult to ascertain. Some of these 

 eggs contained what were apparently normal chalazae. Most 

 of them contained coagulated fibers which resembled the fibers 

 of which chalazae are formed. It is possible that in some or 

 all of these cases a normal yolk has entered the duct, stimu- 

 lated the upper duct to secrete chalazae and some albumen, 

 passed as far as the obstruction and then been extruded, leav- 

 ing behind sufficient chalazae and albumen to furnish the 

 mechanical stimulus necessary for the completion of the egg. 

 Some of these eggs contained lumps of hardened albumen which 

 may have arisen from albumen left in the duct or abnormally 

 secreted. When the ovary is in a particular condition such a 

 mechanical stimulus may cause the secretion of the egg en- 

 velopes. It must be kept in mind, however, that a dwarf egg 

 did not occur unless the ovary was actively producing yolks. 

 In none of the above mentioned cases was it impossible that 

 a yolk had entered the duct and started the formation of the 

 egg- 



B. EVIDENCE FROM THE EGG RECORDS AND AUTOPSY RECORDS OF 

 NORMAL DWARF EGG PRODUCERS WHICH WERE AUTOPSIED. 



Attention has already been called to the fact that while oc- 

 casional cases occur where dwarf egg production is due to a 

 permanent disturbance of the reproductive apparatus it is in 

 general not associated with such a condition. In fact a dwarf 

 egg may occur at any time in a clutch or litter. The production 



