No. 2. — CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 

 OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE, UNDER THE DIRECTION OF E. L. MARK, No. 150. 



The Development of the Mesonephros and the Midlerian Duct 



in Amphibia. 



By KoBEKT W. Hall. 



CONTENTS. 



PAGE 



I. Introduction 32 



Material and metliods .... 36 

 II. Development of the mesone- 



pliros 39 



A. Amblystoma 39 



Stages I- VIII 39-47 



The dorsal extent of the so- 

 matic and splanclmic layers 



of the lateral mesoderm . 47 



Development of a mesonephric 

 unit in Amblystoma com- 

 pared with that in Pristiurus 49 



Later development of the me- 

 sonephric units 50 



Origin of the dorsal sets of 

 units 52 



Later development of the dor- 

 sal sets of units .... 53 



Nephrostomes of secondary 

 units 54 



Description of Table 1 and 

 Diagram 1 55 



Primary and secondary units 

 in Amblystoma and Ichthy- 

 ophis 59 



Relations between sexual and 

 secretory portions of the 

 mesonephros 61 



B. Rana 62 



Development of primary, and 



origin of secondary, blas- 



tulae 66 



Outer tubules and nephros- 

 tomes 69 



VOL. XLV. — NO. 2 



FAOE 



Order of appearance and num- 

 ber of primary units . . . 



C. Comparison of the mesone- 



phric fundaments of Ambly- 

 stoma and Ichthyophis . . 



D. Recapitulation of the meso- 

 nephric development . . . 



Amblystoma 



Rana 



III. Development of the Miillerian 

 duct 



A. Amblystoma 



Larvae I-XII 7 



B. Rana 



C. Hyla 



D. Comparison with the results 

 of other writers .... 



Urodela — Fiirbinger, Hoff- 

 mann, Wilson, Gemmill 



Gymnophiona — Semon 



Anura — Hoffmann, MacBride, 

 Gemmill 



Aniniota : Mammalia — Kip. 



E. Theoretical considerations . 



F. Recapitulation of the devel- 



opment of the Miillerian 



duct 



Amblystoma 



Rana sylvatica 



Hyla versicolor 



Addendum 



Bibliography 



Explanation of Plates 



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