396 MANUAL OF HISTOLOGY. 



are much divided as to its true significance. Some histologists 

 regard the striae as indicating so many minute pores i'or pur- 

 poses of absorptive transmission ; others believe that the jux- 

 taposition of numerous delicate rods explains the peculiar ap- 

 pearance ; and Klein has lately asserted them to be merely 

 prolongations of the fibrils of the cell-substance composing 

 the epithelia. These striae are always seen to run parallel to 

 the long axis of the cells. 



Kraus"e also described as of normal occurrence, a basal pro- 

 cess extending at an obtuse angle from the attached surface of 

 these bodies, and inserted into the delicately serrated border 

 of the villi. Near its attached border each epithelium presents 

 a bright ovoid nucleus, with one or more distinct nucleoli. 

 Besides the ordinary corpuscles, we find interposed between 

 them the so-called goblet- cells. These are derived from the 

 former by mucoid infiltration of the cell-body, which is there- 

 fore conspicuously bulged out. Lymph-corpuscles also occur 

 between the epithelia. 



Immediately beneath this layer we find a delicate, homo- 

 geneous' basement-membrane, composed of flattened cells, re- 

 sembling endothelia. 



The muscularis mucosce, or muscle of Briicke, is made up of 

 a single or double layer of smooth muscle-cells. When double, 

 an inner circular may be distinguished from an external longi- 

 tudinal coat, both being always very attenuated. 



The submucous layer is formed of connective tissue, the 

 supporting framework of which contains lymphatics, blood- 

 vessels, nerves, and often groups of fat-cells. 



The glands of the small intestine are those of Brunner and 

 the crypts of Lieberkuhn. In addition to these, however, there 

 occur numerous lymphoid follicles, which, when found singly, 

 are known as the solitary follicles, and, when grouped together, 

 as agminated glands, or Peyer^ s patches. The solitary or 

 closed follicles are real lymphoid glands, and, like these, con- 

 sist of reticulated connective tissue, the meshes of which are 

 replete with lymph-corpuscles. The jejunum, ileum, and colon 

 all contain such follicles, but the agminated glands occur in 

 the ileum, abounding especially at its lower part. Around 

 each follicle we find a ring of villi and glands, which arrange- 

 ment goes by the name of corona tubulorum (Miiller). The 

 follicles receive an enveloping layer of fibro-connective tissue. 



