ORGANS OF THE BODY. 



487 



seated immediately under the mucosa. Thus they extend as far as the 

 orifice of the ductus clwledochus, and from that point on appear more 

 rarely. Among the mammalia much variety is observed as regards thuoe 

 organs. When only slightly developed, as is frequently the case, they are 

 confined to the neighbourhood of the 

 pylorus, forming a complete zone just 

 behind it. The diameter of these 

 glands ranges from -2 3 to 2 mm. The 

 branches of the excretory ducts present 

 a complicated series of twists unlike 

 other glands of the same kind 

 (Schivalbe). The aoini are round, 

 elongated, or even tubular, and measure 

 from 0-0564 to 0'1421 mm. The ex- 

 cretory canals of these glands, con- 

 siderable in calibre (fig. 477), ascend 

 obliquely upwards, slightly bent, dis- 

 charging their contents at the base of 

 the villi (fig. 477, c). 



Both excretory duct and gland 

 vesicle are, strange to say, lined by 

 the same species of cells. These are 

 low columnar elements, whose nucleus is situated low down in the body, 

 and which are but very slightly coloured by carmine. They are unlike 

 the contents of the follicles of Lieberkuhn soon to be described. 



Fig. 476. Very slender villus from the intestine 

 of a kid, killed while engaged in digestion ; 

 without epithelium, and showing the absorb- 

 ent vessel in the centre filled with chyle. 



Fig. 477. Brunner's glands from the duodenum, a, villi ; b, bodies of glands ; 

 c, excretory canals opening between the villi. 



That same network of extremely delicate gland canaliculi we have 



already spoken of as occurring in many racemose organs ( 195), as well 



as in the salivary glands ( 245), is to be found also in the glands of 



Brviwer, according to Sehwalbe. The membrana propria, which is here 



32 



