DEVELOPMENT OF THE ALBINO RAT 215 
measures 2.8 cm. and contains four ova in the 4-cell stage, situ- 
ated at the beginning of the last loop leading to the uterine 
horn, 2.25 em. from the fimbriated end, thus in the fourth seg- 
ment of the oviduct as of Sobotta’s designation. In figure 14 
is reproduced a detailed reconstruction of the segment of the 
oviduct containing the ova, with the convex portion of the wall 
of this loop, as shown in figure 13, removed. The section re- 
produced in figure 12, passes through the lower of the three 
upper ova, shown in reconstruction in figure 14. In the figure of 
the reconstruction as also in that of the section, is shown the 
groove in which these three ova he. The other oviducts con- 
Fig. 14 Model of the segment of the right oviduct, rat No. 50, 3 days, 1 hour, 
containing the four ova in the 4-cell stage, the general position of which is shown 
in figure 13. The convex portion of the wall of the loop containing the ova is 
removed, so as to expose the lumen. 
taining 4-cell stages were reconstructed graphically, beginning 
with the uterine end. The position of the ova in each is essen- 
tially as given in the model reproduced in figure 13. 
8-cell. stage. In rat No. 57, killed 3 days, 17 hours after the 
beginning of insemination, there are found in the left oviduct, 
six segmented ova in the 8-cell stage and one segmented ovum 
in the 11-cell stage. The right ovary and oviduct was injured 
in the process of embedding and could not be used for sectioning. 
The ova are spaced in the loop of the oviduct which terminates 
in the uterine horn. Six of the segmented ova were recon- 
structed, the seventh was not detected at the time the recon- 
structions were made. The six models obtained are reproduced 
