THYRSOPTERIS. 



[ 766 ] 



THYROID GLAND. 



with simple, swollen, traversing canals, and 

 fascicules of smaller tubes (2 species, Ter- 

 tiary) : 4. Gi/roporella ; cylindrical, with 

 circular canals (14 species, Triassic and 

 Neocomian) : 5. Utena ; annular, hollow, 

 perforate (1 species, Tertiary). 



BIBL. Giimbel, Abhandl. k. bayer. Akad. 

 Wiss. II. Cl. xi. 1872, p. 231. 



THYRSOPTERIS, Kunze. A genus of 

 Cyathese (Polypodiaceous Ferns), with glo- 

 bose, marginal sori, collected into a panicle 



Fig. 741. 



Fig. 742. 



Thyrsopteris elegans. 



Fig. 741. A fertile pinna. 



Fig. 742. A pinnule converted into a cup-like sorus. 

 Magnified 20 diameters. 



distinct from the sterile pinnae. ^Capsules 

 sessile, on a globose receptacle; indusium 

 inferior, cup-shaped, the mouth entire. T. 

 eleyans, tropical. (Hooker, Syn. 15.) 



Fig. 743. 



Fig. 744. 



Thyrsopteris elegans. 



Fig. 743. Vertical section of the same, with the spo- 

 ranges removed from the columella. 



Fig. 744. Side view of a sporange. Magn. 100 diams. 



THY'ROID GLAND. The thyroid gland 

 is one of the vascular glands, or glands with- 

 out ducts. 



It consists of rounded, closed, glandular 

 vesicles (fig. 745) surrounded by or imbedded 

 in a fibrous stroma (a), and aggregated into 

 roundish, elongate, or somewhat polygonal 

 acini or minute lobules, these being grouped 

 in secondary lobules, which unite to form 





G-landular vesicles from the thyroid gland of a child. 

 a, intervening connective tissue; 6, basement mem- 

 brane ; c, epithelium. 



Magnified 250 diameters. 



lobes. The vesicles are from 1-600 to 1-240" 

 in diameter, the acini from 1-50 to 1-24' '. 

 The stroma is condensed around the lobules, 

 to form a fibrous coat. 



The stroma consists of ordinary interlacing 

 bundles of connective tissue, with fine elas- 

 tic fibres, at its outer surface containing fat- 

 cells. 



Fig. 746. 



Glandular vesicles with colloid matter 

 Magnified 50 diameters. 



The vesicles consist of a basement mem- 



