The pronephros of Chrysemys marginata. 89 



Plate 3. 



Fig. 33. (Section 4.34.) Notice the condition of the glomus on 

 each side in this figure. 



Fig. 34. (Section 4,35.) A pronephric tubule on the left side is 

 passing into the duct in this figure. 



Fig. 35. (Section 4,36.) On each side a tubule is cut through. 

 The remains of the nephrotome are visible on the right side. 



Fig. 36. (Section 5,7.) A nephrostorae is visible on the embryo's 

 right side : a tubule is opening into the pronephric duct on the left side. 



Fig. 37. (Section 5,9.) The glomus is fusing with the somatic 

 mesoderm lateral to the nephrostome shown on the left of this section. 



Fig. 38. (Section 5,14.) Figs. 38 to 52 are photographs of suc- 

 cessive sections through segments XI and XII of Embryo M. In Fig. 38 

 notice the nephrotome on each side and its relation to the tubule nephro- 

 stome on the right side of the figure. 



Fig. 39. (Section 5,15.) On each side the glomus is showing signs 

 of fusion beneath and lateral to the opening of a pronephric tubule. 



Fig. 40. (Section 5,16.) Notice that the glomus is becoming more 

 dorsal relatively to the kidney tubules. 



Fig. 41. (Section 5,17.) Shows a tubule cut across on each side: 

 the nephrotome is quite shut in on the right side of the figure but open 

 on the left. 



Fig. 42. (Section 5,18.) On the left side the region where vas- 

 cular tissue has fused beneath the nephrostome is swollen by the presence 

 of blood corpuscles. 



Fig. 43. (Section 5,19.) The lower end of the nephrotome is again 

 visible in this figure on the right side. 



Fig. 44.- (Section 5,20.) On the animal's left side the swollen 

 nephrocoel is clearly visible, and the position of the nephrostome of a 

 tubule is marked as a thickening on the lateral outer wall of the 

 nephrotome. 



Fig. 45. (Section 5,21.) Shows a nephrostome opening into a 

 nephrocoel cut across on each side. 



Fig. 46. (Section 5,22.) Passes through a pronephric (?) tubule on 

 each side. 



Fig. 47. (Section 5,23.) Passes through a pronephric (?) tubule on 

 each side. 



Fig. 48. (Section 5,24.) A nephrostome opening into a nephrotome 

 is cut through on each side. 



Plate 4. 



Fig. 49. (Section 5,25.) On the left side of the figure a tubule 

 is cut longitudinally. 



