Hall. — Mesonephros in Amphibia. 



PLATE 1. 



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



Fio. 1. Stage I. A section through the middle of the seventh somite of the right 



side of the body. X 100. 

 Fig. 2. Stage IV. Through tlie middle of the seventh somite of the left side. 

 Fig. 3. Stage II. Through the middle of the sixth somite of the right side. 



X 100. 

 Fig. 4. Rana. Through the ninth (lower) and tenth (upper) somites of the left 



side. X 280. 

 Fio. 5. Stage II. Through tlie iniddle of a somite of the right side, showing the 



germ cells in both layers of the lateral mesoderm. X 250. 

 Fig. 6. Rana. Through the anterior half of the sixth somite of the left side of 



a larva 3.25 mm. long. X 280. 

 Figs. 7, 8, 9. Stage V. Three sections through somites of the right side of the 



body. X 335. 

 Fig. 7. Cuts somites 11 and 12. 

 Fig. 8. Passes through the middle of somite 13. 

 Fig. 9. Passes through the posterior end of somite 13. 

 Figs. 10, 11, 12. Stage VI. X 335. 



Fig. 10 represents a section through the thirteenth somite of the right side. 

 Figs. 11, 12 represent sections through the twelfth somite of the left side. 



