DEVELOPMENT OF THE ALBINO RAT 



19 



to view in the aspect of the model sketched. The position of 

 the first and the last of the series is correctly given. The ova 

 are situated in a loop of the oviduct which is about 8 mm. from 

 the fimbriated end. By the end of the first day after the begin- 

 ning of insemination, the ova have thus travelled about one- 

 fourth the length of the oviduct. In figure 4 is reproduced a 

 model of a detailed reconstruction of that portion of the oviduct 



Fig. 4 Model of the segment of the right oviduct of rat No. 106, 24 hours, 

 containing the ova the general position of which is shown in Figure 3. X 50. 

 The wall is in part removed, so as to expose the lumen. Note the character of 

 the folds of the mucosa. The relative position of the eight contained ova, all 

 in the pronuclear stage, is clearly shown. 



containing the ova, representing a loop of the tube with one 

 side cut away, this to show the extent and character of the 

 mucosal folds, the width of the lumen and the relative position 

 of the several ova. The figure presents these facts so clearly 

 that lengthy description is deemed unnecessary. The several 

 ova are distributed through a tube segment measuring about 

 2.5 mm. in length. They lie free in the lumen, apparently bathed 

 in a fluid from which there is only a small amount of precipita- 

 tion at the time of fixation. Their position in the oviduct at 



