39^ THE THYROID GLAND. [SECT. 180. 



landischen Beitr'dgen, i. p. 7. Rossignol, Recherches sur la Structure Iniime du 

 Poumon, Brux., 1 846. S. Adriani, De Subtiliori Pulmonum Structura, Trajecti 

 ad Rheu., 1 847, Diss. H. Cramer, De Penitiori Pulmonum Hominis Structura, 

 Berol., 1847, Diss. E. Schultz, Disquisitiones de Structura et Textura Cana- 

 lium Aeriferorum, c. tab., Dorpati Liv., 1850, Diss. Kostlin, in Tubing. Arch., 

 1848, part iv. p. 292, and part ii. p. 167. A. Ecker, Icon. Phys., tab. xxi. 

 Rheiner, in the Wiirzburg Transactions, iii., and Beitrdge zur Histologic des 

 Kehlkopfs. Diss, inaug. Wiirzburg, 1852. L. Beale, On the Blood-vessels of 

 the Lungs, in Monthly Journal, 1852, p. 454. G. Rainet, On the Epithelium of 

 the Air-cells, Brit, and For. Med.-Chir. Rev., Oct. 1855. F. Williams, Epi- 

 thelium of Air-cells, Med. Times and Gaz., 1855, p. 361. A. Biermer, Die 

 Lehre vom Auswurf, Wiirzb., 1855. C. Radclyffe Hall, On the Epithelium, 

 etc., in Brit, and For. Med.-Chir. Rev., July, 1857. 



Of the Thyroid Gland. 



§ 180. The thyroid gland is one of the so-called 'ductless 

 glands,' and bears in its external appearance a considerable resem- 

 blance to the racemose glands. Its gland-vesicles are round shut 

 sacs, measuring from o'02 ,// to o - 05'", which are held together in 

 lobules by a fibrous stroma. The lobules thus formed, the gland- 

 granules of some authors, are roundish or oval, or somewhat poly- 

 gonal, and measure £'" to %". These elements unite into larger 

 lobes, and these again congregate into still larger divisions, which 

 are seen on the surface of the organ. These divisions are bounded 

 by a special envelope of some thickness j which is connected with a 

 fibrous coat enclosing the whole gland. 



With reference to its intimate structure, there is. not much to 

 be said about the fibrous tissue, or stroma of the thyroid, for it 

 consists of ordinary interwoven bundles of connective tissue, min- 

 gled with fine elastic fibres. A certain number of fat-cells are also 

 found upon the surface. The gland-vesicles themselves present 

 such an inconstant structure in the human thyroid, that it is not 

 easy to say what is properly normal. According to my own obser- 

 vations in man and in the lower animals, they appear to consist 

 of a memhrana propria, an epithelium, and fluid contents, like 

 the true gland- vesicles, of the mucous glands for instance. The 

 membrane is quite homogeneous, clear, and delicate, o - ooo8'" in 

 thickness; like all such membranes, it swells up and comes out 

 more distinctly on the addition of caustic alkalies. Upon the 

 inner side of the membrane is situated a simple layer of epithelium, 

 composed of polygonal, finely granular, clear cells, of o'OO^" to 

 O'oob'" in diameter, with simple nuclei. The cavity enclosed by 



