250 ELEMENTARY PHYSIOLOGY. [XXIV. 



or alcohol, to observe the structure of the sweat- 

 glands. Note 



a. The terminal gland-coil in the outer part of 

 the subcutaneous tissue, with its membrana 

 propria continuous with that of the dermis, 

 and lined by a single layer of cubical or 

 short columnar cells. 



b. The gland-duct having two or three layers 

 of cells continuous with those of the Mal- 

 pighian layer of the epidermis. The lumen 

 is usually distinct in both duct and coil. In 

 the epidermis the cells proper to the duct 

 cease but its lumen is continued on in a 

 spiral course to the surface surrounded by 

 concentrically arranged epidermic cells. 



3. In the specimen of the cornea of the frog pre- 

 pared as in Lesson v. B 2 (cp. also Lesson x. 

 2) observe 



a. The primary nerve-plexus formed by the 

 bundles of nerves which enter the cornea at 

 its periphery; this plexus has in its deeper 

 part rather large meshes and its fibres have 

 nuclei on their course ; towards the surface, 

 and especially just beneath the anterior 

 basement membrane, this plexus becomes 

 much finer consisting chiefly of small bundles 

 of nerve-fibres with much less frequent nuclei; 

 when these occur they are usually at the 

 nodal points of the plexus. 



