ON THE ENTERON OF AMERICAN GANOIDS. 



GRANT SHERMAN HOPKINS, B. S. 



CONTENTS. 



PAGE 



Historical Sketch 411 



Material and its Preparation 416 



acipenser 417 



Scaphirhynchops 422 



polyodon 424 



Lepidosteus 426 



Amia 430 



Summary 432 



References 435 



Explanation of Plates 440 



Historical Sketch. 



The history of the successive discovery of facts relative to 

 the morphology of the enteron in the vertebrates may be said 

 to have undergone a process of evolution comparable to that 

 through which the forms with which it deals have passed. 



The first stage may be comprised between the years 1836 

 and 1869. "In 1836, Dr. Sprott Boyd (9),^ in attempting to 

 discover whether or not there existed an internal membrane of 

 the stomach below that of the mucosa, failed to find what he 

 sought, but saw the mucosa covered uniformly with small tubes, 

 which he described and figured in several species of mammals, 

 birds, and reptiles. The openings of these glands had been 

 seen previous to the year 1836, and also isolated follicular or 

 glandular masses had been noted, but Boyd was the first author 

 who saw the mucosa of the stomach entirely covered with tubu- 

 lar glands from the cardia to the pylorus." 



In 1838, Henle and Purkinje (51) each found that these 

 glandular tubes were lined with cells; a year later, Wasmann 



1 See References. 



