DEVELOPMENT OF THE ALBINO RAT 25 



applied to the outside of the ovarian capsule, and conspicuous 

 in all of the figures of models of the oviducts here presented. The 

 detail of the distribution of the ova in the tube is given in figure 

 8, a reconstruction under a higher magnification of the segment 

 of the oviduct containing the ova. The Lumen is exposed so 

 that the character of the mucosal folds may be seen. The ova 

 are spaced in a segment of the tube measuring 3 mm., and are 



Fig. S Model of the segment of the right oviduct of rat No. 59, 2 days, con- 

 taining the four 2-cell stages as shown in figure 7. X 50. Note the absence of 

 prominent folds in the mucosa. The segment presented in the reconstruction 

 measures 3 mm. The four 2-cell stages contained in this tube are relatively 

 widely spaced. 



in this case more widely separated than is usual for this stage. 

 In figure 9, there is reproduced a reconstruction of the left ovi- 

 duct of rat No. 62, killed 2 days, 22 hours after the beginning 

 of insemination. This tube was also cut a little before its in- 

 sertion into the uterine horn. The portion reconstructed meas- 

 ures 2.45 cm. In it there are found five ova in the 2-cell stage, 

 situated about 2 cm. from the fimbriated end, and in the last 

 loop of the third segment of the oviduct. The five ova are closely 



