HISTOGENESIS AND HISTOLYSIS OF THE INTESTINAL 

 EPITHELIUM OF BUFO LENTIGINOSUS. 



BY 



MAKY A. BOWERS. 



With 4 Plates and 1 Text Figure. 



The various phenomena associated with metamorphosis present 

 many problems which are of great biological interest. They have 

 attracted a large number of investigators, and the literature, includ- 

 ing all phases of the subject, the macroscopic and microscopic 

 changes which occur at the time of transformation and the experi- 

 mental and theoretical work on the causes of metamorphosis, has 

 become most voluminous. However, previous to 1906 but two papers 

 had been published on the modification of the tadpole intestine, 

 Ratner, '91, and Renter, 1900. Ratner describes the changes which 

 occur in the subepithelial layers; Renter, using Alytes obstetricans, 

 gives a very full account (Part I) of the macroscopic changes of 

 the alimentary tract; (Part II) the degenerative and regenerative 

 modifications of the epithelium. I should mention that Kingsbury, 

 '99, published a brief abstract of work which he had begun on 

 Bufo. Since my work was begun another paper has appeared, by 

 Duesberg, '96, but as his observations and interpretations are not in 

 accord with those of Renter and as his material, Rana fusca, is dif- 

 ferent from mine, it seems worth while to state briefly my results. 



This investigation was undertaken at the suggestion of Professor 

 E. G. Conklin, and has been carried on in the laboratories of the 

 University of Pennsylvania. I wish to express my sincere appre- 

 ciation of Professor Conklin's valuable assistance and his kindness 

 to me throughout my work. I am also greatly indebted to Mr. 

 Herbert G. Kribs, who most carefully prepared the photomicro- 

 graphs and kindly aided me in all my photographic work. 



The American Journal of Anatomy. — Vol. IX, No. 2. 



