34 G. CARL HUBER 



of the drawing, and greatly occluding the lumen, is the fold re- 

 moved in the model. In this very fortunate section four of the 

 morula masses are included; all are of the 8-cell stage and repre- 

 sent in section the four ova which are placed closely together as 

 seen in the model figured in figure 16. In figure 19, A, there is 

 reproduced at higher magnification another of the sections of 

 the series, including the right one of the three ova in close apposi- 



Fig. 18 Model of the left oviduct of rat No. 51, 4 days. X 10. A short 

 segment of the upper end of the uterine horn was included in the reconstruction, 

 lower end of the figure. The position of three of the morula masses, 12-cell to 

 16-cell stages, in the terminal part of the oviduct is to be noted, a further one is 

 located in the upper part of the uterine horn. These are shown as if seen through 

 a transparent wall. A fifth morula, situated in the uterine horn about 1.5 cm. 

 from the entrance of the oviduct, is not included in the figure. 



tion as seen in figure 17, showing six of the eight cells, each cut 

 in the plane of its nucleus. In both of these figures (figs. 17 and 

 19) the morula masses, as seen in the sections drawn, present a 

 quite regular oval outline. In succeeding sections, in which 

 the mucosal fold and the wall of the oviduct approximate, the 

 cross diameter of each of the four morula masses becomes greatly 

 reduced, they appearing in the final sections of the series in which 

 they are included as narrow, non-nucleated bands of protoplasm. 



