110 
DIGESTIVE APPARATLS. 
Stomach a prolongation (Fig. 4/, Ji) {zapfen) like a 
tube, containing nucleated cells, with a delicate mem- 
brane (/) which extends beyond these. This, Schiemenz 
says, when food is not passing through it, falls on one 
side and closes the opening, acting as a valve. The 
prolongation is in reality an infolding of the membrane 
of the chyle stomach, and its real use will be explained 
in the next chapter, when treating of brood food. 
The chyle stomach bends upon itself from right to 
left, and is constricted at regular intervals by ring 
muscles (Fig. 47, k)^ longitudinal muscles (/) running 
along the whole length. 
It is lined by an inner membrane {intima)^ with a 
layer of nucleated cells (;;/ m) of various forms, which 
Schiemenz thinks have different functions, such as 
secretion of gastric juice and absorption, and outside 
this is an outer membrane {propria). The chyle 
stomach has a brownish appearance, from the pollen 
grains usually contained in it, and Schiemenz con- 
cluded that the object of the intima, which is tolerably 
strong, is to prevent these, or their skins, from coming 
directly into contact with the secreting cells, from 
amongst which it would be difficult to separate them. 
By the action of the juice produced by these gastric 
glands upon the food, in the process of digestion in 
the chyle stomach, it is changed into chyme. This 
first stomachial digestion is called chymification. 
The muscular walls acting upon the portion of 
unabsorbed chyme force it into the much narrower 
small intestine. At the commencement of this are 
a number of long tubes ( frontispiece, I ), which 
