116 RAYMOND PEARL AND MAYNIE R. CURTIS 
As stated in the preceding paragraphs the points on the time 
or abscissal axis represent the mean or average results of fairly 
extensive experimental data, some of which are not included in 
the present paper. NNow we may consider the determination of 
the points plotted as ordinates. At the outstart it should be said 
that no observations have yet been made on the rate of secretion 
of albumen at different levels of the ‘albumen portion’ itself. 
Therefore from the zero point at ‘ovulation’ when the naked yolk 
enters the infundibulum to the beginning of the isthmus we have 
connected the points with a dotted line to indicate that in this 
region no direct observations are available. The first plotted 
point (40.4) at the beginning (cranial end) of the isthmus is the 
mean albumen percentage of three eggs which were taken from 
this point in the duct. The next point plotted is the mean albu- 
men percentage (50.6) of four isthmus eggs which were taken from 
the upper part of the isthmus. The next point (53.8) is the mean ~ 
albumen percentage of four isthmus eggs taken from the lower 
part of the isthmus. The last six points are based on the obsery- 
vations of single eggs which have been in the uterus the indicated 
length of time. 
The smooth curve which graduates these observations is the 
parabola 
y = 17.5915z — 0.81712? — 0.4164, 
in which y denotes percentage of albumen and 2 time in hours 
during which the egg has been in the oviduct. The origin of x 
is taken atO (ovulation). The parabola was fitted to the observa- 
tions by the method of least squares. 
The diagram shows clearly that there is scarcely any diminu- 
tion in the rate of secretion of albumen until nearly the total 
amount has been acquired by the egg. There is not the slightest. 
evidence of any break in the rate of secretion of albumen after the 
egg leaves the so-called ‘albumen portion’ of the duct. From the 
time the yolk enters the upper end of the ‘albumen portion’ there 
is a gradual diminution of the rate of secretion of albumen, giving 
rise to the parabolic curve. But plainly there is no sudden 
change. The egg gets more than half of its total albumen after 
