Field. —Pronephros in Amphibia. 



PLATE VI. 



Fig. 47. A portion of a cross section througli the anterior trunk region of a larva 

 of Bufo belonging to Stage V. The Figure shows the pronephric 

 structures in a region between the first and second nephrostomes, 

 X 158. 



Fig. 48. A portion of a cross section tlirough the middle trunk region of an em- 

 bryo of Amblystoma belonging to Stage I. X 65. 



Fig. 49. Anterior face of a cross section through the glomus of a larva of Bufo 

 belonging to Stage V. X 470. Zeiss apocr. 4 mm. Oc. 6. 



Fig. 50. Anterior face of a portion of a cross section through the right glomus of 

 the same larva, including also the opposite peritoneal wall. X 710. 

 Zeiss apochr. 4 mm. Oc. 12. 



Fig. 51. A cross section^(right side, anterior face) through the pronephros repre- 

 sented in Figure 37. The section passes directly in front of the 

 third nephrostome, and shows the expanded region of the common 

 trunk at the level of its union with the collecting trunk. X 90. 



Fig. 52. A portion of a cross section through the glomus of a larva of Bufo be- 

 longing to Stage V. The Figure shows an infolding (opposite the 

 letters cceL") of the outer peritoneal layer of the glomus. X 500. 



