198 EXPLANATION OF THE PLATES. 



are very few ; 4, external coat, made up of connective, elastic, 

 and muscular fibres ; the latter (5) run parallel with the axis of 

 the vessel. 



FIG. III. A longitudinal section of the same lymphatic. 

 1, Middle coat ; 2, muscular fibres seen in transverse section ; 

 3, nuclei ; 4, external coat ; 5, nuclei of muscular fibres encircling 

 the vessel. 



FIG. IV. Recent specimen of a valve treated by acetic 

 acid. 1, Nuclei of epithelial cells; 2, elastic fibres; 3, nuclei of 

 muscular fibres. 



FIG. Y. Section of a lobe of the sub-lingual gland 

 magnified 80 diameters. 1, Excretory duct; 2, its radicles, one 

 of which belongs to each lobule ; 3, cavity of one of the coecal 

 pouches of which the gland is composed ; 4, connective tissue 

 surrounding its walls. 



PLATE XVIII. 



GLANDS COMPOSED OF CLUSTERED FOLLICLES. 



FIG. I. Three co3cal pouches of the sub-lingual gland, 

 lined by thin epithelium. The nucleus (1) almost fills each of 

 the epithelial cells. 



FIG. II. Sebaceous follicle from the scrotum. 1, Cavity 

 of the follicle filled with cells ; 2, young cells containing nuclei, 

 and immediately in contact with the walls of the cavity; 3, 

 other cells, of greater age, in process of fatty transformation ; 

 4, excretory duct filled with minute globules of fat; 5, con- 

 nective fibres enveloping the follicle ; 6, epidermis. 



FIG. III. Sebaceous gland from the external auditory 

 canal. 1, Body of the gland presenting irregular pouched pro- 

 jections (2) ; 3, excretory duct. 



FIG. IV. Cells from a sebaceous gland showing different 

 stages of fatty infiltration. 



FIG. V. Epithelium from a Meibomian gland 1, 

 Young cells ; 2, older cells, filled with oil globules. 



