126 



THE HUMAN SPECIES 



of the lamina propria, the mucosa from '8 to i mm. in thickness 

 with numerous conical papillae, and, lastly, the stratified pave- 

 ment epithelium. 



The stomach of the vertebrates is more complex in structure 

 than that of the invertebrates, and the most highly differentiated 

 is that of the mammals, where the essential differences may be 

 observed with the naked eye. The case of the seal offers the 

 sole exception to the general transverse position of the stomach 

 A stomach in the form of a caecal sac produced by a high de- 

 velopment of the curvature is absent in most of the carnivora, 

 but is not peculiar to man (see Fig. 68) and the apes, since it 



Lig. rotund 

 Gallbladder 



Left hepatic lobe (seen from below 



Stomach 



Right lobe 



Spleen 



Pancreas 



Duodenum 



FIG. 68. Liver, stomach, spleen and pancreas (liver and stomach laid open). 

 (Ranke, Der Mensch.) 



is found fairly well developed in the monotremata, marsupials, 

 edentata and rodents. Further, it is not only in man but in 

 many other of the mammals that the so-called ante-stomach is 

 absent, whether, as in the horse and pig, it takes the form of 

 a portio cesophagea or, as in the ruminants, be divided by 

 transverse constriction into cardia and pylorus with the accessory 

 secondary expansions. In all cases there are histologically five 

 strata to be distinguished, namely : the mucosa with its epithe- 

 lium, special glands and lamina propria, the submucosa, the 

 muscularis, the subserosa and the serosa. Those glands situ- 

 ated in the fundus and hence called fundus glands are of a 



