l80 C. M. CHILD. 



Explanation of Plate VIII. 



Fig. i. A very early stage of the developing genital ducts in the region lateral to 

 the longitudinal nephridial canals. The width of the figure from right to left repre- 

 sents approximately the width of the region involved in proliferation and the axis of 

 the duct corresponds with a line through the middle of the figure from top to bottom 



Fig. 2. A somewhat later stage in the development of the genital ducts, from the 

 same region and showing one case of mitosis. Plane of section as in Fig. I. 



Fig. 3. The developing vas deferens near its inner end. The width of the figure 

 represents the width of the proliferating region. Plane of section as in Fig. I. 



