DEVELOPMENT OF THE ALBINO HAT 31 



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 cm. 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 lie. 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 



