SHAPE AND STRUCTURE OF ALIMENTARY VISCERA OF PORPOISE. 321 



and set in intimate contact with the basement membrane, which sent prolongations 

 inwards between them towards the central cells. As a result, each of the parietal cells 

 occupied a recess or pocket exactly as if it lay in one compartment of a honeycomb. 

 The parietal cells were not quite so large as the central cells, and from the fact that the 

 former separated quite readily from the latter, one judged that there was no very definite 

 uniting medium. The products of the activity of the parietal cells would find their 

 way into the lumen of the tubule through fine interstices between the central cells, and 

 these interstices were visible or concealed according to the direction of the section. 

 Each parietal cell might be regarded as a unicellular secreting gland. They were filled 

 with coarse eosinophile granules. It is important to note that these cells formed an 

 unbroken layer, and that they were situated next to the blood supply, and that, therefore, 

 they intervened between the central cells and their direct blood supply. In presenting 

 a continuous layer of parietal cells, these tubular glands differ from those with which 

 they correspond in such animals as the dog, the bat, and even in man, in all of which 

 they only occur at intervals in the walls of the tubules. It is also of interest to note 

 that these oxyntic cells are definitely restricted to one compartment of the stomach of 

 the porpoise, whereas in the single-chambered stomachs of the other mammals above 

 referred to, they are specially characteristic of the fundus, although not exclusively 

 confined to that region. 



The intertubular stroma everywhere showed very well marked capillary vessels, and 

 throughout the stroma, more especially towards the free side of the mucous membrane, 

 numbers of lymph cells were scattered. 



From the ventral aspect of this compartment, and about one inch (2 "5 cms.) in front 

 of its most dependent part, a small constricted passage, wide enough to transmit the 

 handle of a rod 5 mms. in diameter, led into the third compartment (PI. III. fig. 10b). 

 This passage was quite concealed among the thick muscular rugse of the second 

 chamber, and its exact position would scarcely be suspected from an examination of 

 the second chamber. Viewed from the third compartment, however, it presented the 

 appearance of a small firmly constricted aperture opening backwards. We feel assured 

 that this is nothing more than a mural passage from the second to the third chamber. 

 Tt has been regarded by Jungklaus as a separate chamber, supplying in itself the 

 third chamber, which has long been sought for in order to complete the analogy 

 between the stomach of the porpoise and that of other cetacea. But the necessity 

 for doing this disappears, since the method we have employed reveals the presence of 

 a distinct globular third chamber, entirely separate from the second and fourth com- 

 partments, and outside of the mural passage, which is required as an outlet from the 

 second to the third compartments. The third compartment was situated somewhat 

 behind and on the ventral aspect of the second, to which it was closely adherent by the 

 surface next the inlet without the intervention of peritoneum ; but on its dorsal and 

 ventral surfaces the peritoneum was prolonged from the second compartment without 

 interruption, and, moreover, it had the great omentum attached to the hinder border of 



TRANS. ROY. SOC. EDIN., VOL. XL. PART II. (NO. 16). 3 b 



