164 MAINE AGRICULTURAL LXPLRIMLNT STATION. 1:^)13. ' 



vvhether this apparently lower weight of presumably completed, 

 but not laid eggs, as compared with those which has been laid, 

 was a real phenomenon of general occurrence, and if so to 

 what it was due. Does the egg increase in weight after the for- 

 mation of shell membranes and shell merely by the absorption 

 of water or by the actual addition of new albumen? 



Observations and Experiments. 



In the normal egg of the hen there are certainly three and 

 possibly four different albumen layers which can easily be dis- 

 tinguished on the basis of physical consistency. These are : 

 (a) the chalasiferous layer. This is a thin layer of very dense 

 albuminous material which lies immediately outside the true 

 yolk membrane. It is continuous at the poles of the yolk with 

 the chalazse, and is undoubtedly formed in connection with those 

 structures. It is so thin a layer that it might well be, and often 

 has been, taken for the yolk m.embrane. {b) The inner layer 

 of -fluid (thin) albumen. This layer is only a few millimeters 

 in thickness and there is some doubt as to its existence as a 

 separate distinct layer, {c) The dense albumen. This is the 

 layer which makes up the bulk of the "white" of the egg. It is 

 composed of a mass of dense closely interlaced albumen fibres 

 with some thin albumen between the meshes of the fibrous 

 network. The dense albumen as a v/hole will not flow readily 

 but holds itself together in a flattened mass if poured out upon 

 a plate, {d) the outer layer of fluid albumen. This is the prin- 

 cipal layer of thin albumen, which makes up the fluid part of the 

 "white" observed when an egg is broken. 



In order to determine when and where these different layers 

 were added to the egg, particularly the last one (d). hens hav- 

 ing an egg in the oviduct were killed and the location and con- 

 dition of the egg determined. Many such autopsy records agree 

 in showing that the egg does not receive the outer layer of thin 

 Uuid albumen (layer d) during its sojourn in the so-called albu- 

 men secreting portion of the ovnduct. 



A single illustrative protocol may be cited here. Autopsy No. 

 301. Hen No. E. 39. July 14, igc:^. 



When this bird was killed an egg was found at the lower end 

 of the albumen portion of the oviduct just about to enter the 



