108 RAYMOND PEARL AND MAYNIE R. CURTIS 
(items 3, 4, 6, 9, and 15) the weights are given only to one decimal 
place (tenths of a gram). These were eggs studied in the early 
stage of the investigation, and mostly are cases in which the data 
were taken in connection with other studies in progress in the 
laboratory, for which finer weighing was not essential. These 
cases are to be regarded as giving a much rougher sort of data 
than the others tabled, where the weighings are accurate to 
hundredths of a gram. In no instance, however, does one of 
these ‘rough’ cases stand alone. That is, there are one or more 
eges for which finer weighing are tabled from each of the levels 
of the oviduct wherefrom a roughly weighed egg was taken. 
These ‘rough’ cases then serve merely to confirm evidence ob- 
tained from more precise weighing. All differences in the table 
are given the + sign when the oviduct egg or its part is greater 
than the laid egg or its part. The differences are taken — when 
oviduct egg or its part is smaller. The last column of the table 
gives the percentage which the weight of albumen in the oviduct 
egg at the specified level is of the mean total weight of albumen 
in the normal laid egg of the same bird. This last column then 
shows directly what proportion of the total albumen which the 
ege is to have has been laid down at each specified level of the 
oviduct. 
From table 1 the following points are to be noted: 
1. When the egg leaves the albumen portion of the oviduct it 
weighs roughly only about half as much as it does when it is 
laid. Nearly all of this difference is in the albumen. Thus these 
weighings fully confirm the conclusion reached from direct exam- 
ination of the eggs, as described in the preceding section. The 
evidence thus far presented shows that the egg gets all of its thin 
albumen (layer D), which constitutes nearly 60 per cent by weight 
of the total albumen, only after it has left the supposedly only 
albumen secreting portion of the oviduct, and has acquired a 
shell membrane, and the shell is in process of formation. The 
fact that the egg increases considerably in size after it enters the 
isthmus is obvious from simple visual comparison of egg from this 
region of the oviduct with normal laid eggs of the same bird even 
though no weights whatever are taken. 
