SOME FEATURES IN THE DEVELOPMENT OF THE 



CENTRAL NERVOUS SYSTEM OF 



DESMOGNATHUS FUSCA^ 



p. E. SMITH 



From the Department of Histology and Embryology, Cornell University, 

 Ithaca, Neio York 



FIFTY-EIGHT FIGURES (EIGHT PLATES) 



CONTENTS 



Introduction 51] 



Material and methods 512 



Stages 513 



Closure of the neural tube 513 



The pineal region 514 



Description 514 



Discussion 521 



Summary 523 



The development of the hypophysis 524 



Segmentation 527 



Description 529 



Discussion 532 



Summary 534 



General morphology 534 



The fore-brain 535 



The mid-brain 537 



The cerebellum 537 



Literature cited 538 



INTRODUCTION 



Desmognathus fusca is one of the most widely distributed of the 

 eastern urodeles. It was chosen for this study, among other 

 reasons, because: it was easily available; the eggs during 

 earlier stages are not pigmented; and the persistence of embryo- 

 logical characters (Fish '95) and the retention of teleostean charac- 



' The writer wishes to express his appreciation of the help and encouragement 

 received from Prof. B. F. Kingsbury and Dr. William A. Hilton. 



511 



