PHYSIOLOGY OF THE OVIDUCT 107 
THE PROPORTIONATE WEIGHT OF YOLK AND ALBUMEN IN EGGS 
IN DIFFERENT STAGES OF FORMATION 
Having learned by direct observation, as set forth in the 
preceding section that the egg as it enters the isthmus does not 
visibly bear the outer layer of thin albumen, the next step in 
the analysis is to determine whether the amount of albumen (by 
weight) in the egg definitely increases during its sojourn in the 
isthmus and uterus, and if so to what extent. In order to do this 
it is necessary to take eggs at successive intervals after they have 
entered the isthmus, separate and weigh yolk and albumen each 
by itself, and then compare the weights so obtained with the 
weights of yolk and albumen in normal, completely formed and 
laid eggs produced by the same individual birds. Experiments 
of this kind we have carried out with the results described in 
this section of the paper. 
It should be said that the technique followed in the separating 
and weighing of the eggs to furnish these data is that described 
by one of the authors in another place.‘ 
Table 1 gives data regarding the weight of yolk and albumen 
in eggs which have completed their passage through the albumen 
secreting portion of the oviduct, and have advanced varying 
distances into the isthmus and shell gland. The data here given 
are extracted from the more detailed table exhibited in the Appen- 
dix of this paper. 
The plan of table 1 is to compare the weights of the parts of 
a series of eggs taken from different levels of the oviduct with the 
weights of the same parts in normal laid eggs of the same birds. 
Owing to the considerable individual variability in the weights 
of eggs it is only by such comparisons as this that reliable results 
may be reached. To determine the means for the normal laid 
egg varying numbers of eggs were used in different cases. In 
one instance (item 3) only one laid egg was available for compari- 
son. In all other cases the mean of two or more complete nor- 
mal, laid eggs are used. It will be noted that in somecases 
‘Curtis, M. R., Annual Report Maine Agricultural Experiment Station, 1911, 
pp. 93-112. 
