352 ADOLPH R. RINGOEN 
specimen, embedded in paraffin, and cut in serial sections 5 y» 
in thickness. The sections were stained with iron-haematoxy- 
lin. Both erythrosin and orange G were employed as counter- 
stains. For a large part of the prepared Acanthias material 
I am personally indebted to Dr. Richard E. Scammon, who 
has so kindly permitted me to use numerous series from his 
private collection (S. C.). 
It is with great pleasure that I express my appreciation to 
Dr. Scammon for suggesting this investigation, for the loan 
of material, and for the interest shown during the progress of 
this study. I also wish to express my indebtedness to Mrs. 
Helen Sanborn Chapman for the accurate drawings. 
LITERATURE 
Our conceptions of the histogenesis of the glandular elements 
of the digestive tract are based largely on observations made on 
the study of mammalian material. A comprehensive review 
of the literature bearing on the subject would be foreign to the 
purpose of this study. Later an attempt will be made to in- 
dicate the present status of our knowledge in this field, in so 
far only as it may be essential to a clearer understanding of 
gland formation in Squalus acanthias, by brief reference to a 
few papers. 
Sprott Boyd (’36) made the first observations on the presence 
of gastric glands in mammals and fishes. Following Boyd’s ob- 
servation, Bischoff (’38) studied the mucous lining of a great 
many species of fishes. In some species he was unable to find 
glands, while in others they were abundant. 
In 1852 Leydig discovered gastric glands in Squatina an- 
gelus and Torpedo galvani. Later he referred to these glands 
as ‘Labdriisen,’ thinking that they were comparable to the 
gastric glands of mammals. 
Edinger (’77), in studying the mucous membrane of the 
stomach of fishes, was unable to distinguish the chief and cen- 
tral cells as discovered by Heidenhain and Rollet in the mamma- 
lian stomach. According to Edinger, among the Teleosts there 
are a number of forms that possess no glands in the stomach. 
