Hall. — Mesonephros in Amphibia. 



PLATE 2. 



All figures are of cross-sections and are of Amblystoma unless otlierwise indicated. 



Fig. 13. Stage III. Through the middle of somite 13 of the right side. X 335. 



Fig. 14. Rana. Through the anterior half of the seventh somite of the right side 

 of a larva 4.5 mm. long. X 280. 



Fig. 15. Rana. Through tlie last mesoncphric blastula of the left side of a larva 

 8.5 mm. long. X 410. 



Fig. 16. Rana. Through the eiglith somite of the right side. X 380. 



Fig. 17. Stage VII. Through the posterior part of somite 11 of the right side. 

 X 660. 



Fig. 18. Rana. One of the sections from which Figure 102 was constructed. The 

 larva measured 11.5 mm. in length. X 410. 



Fig. 19. Stage VIII. Through the eleventh somites of both sides of the body, 

 showing two mesonephrlc blastulae. X 305. 



Figs. 20-28. Sections of four mesonepliric units. All are from the posterior half 

 of the sixteenth somite. That of Figure 22 is from the right side, the 

 others from the left side of the bod}-. Tlie blastula of Figure 20 is in 

 reality smaller than that of Figure 21, Figure 20 being magnified 500 

 diameters, while Figures 21, 22, 23 are magnified only 340,diameters. 



