THE THYMUS. 589 



the vesicles in detail, and in their mutual relations ; but the same object 

 may also be attained by minute dissection, and the teasing out of the 

 structure. Injections are very easily made and run very finely in 

 children ; they best exhibit the plexuses around the vesicles, in sections 

 taken from the surface. 



Literature. Schwager-Bardelebcn, " Obs. micr. de glandularum 

 ductu excret. carentium structura," Berol. 1841, Diss. ; Pancigiotides 

 and K. Wagoner, "Einige Beobachtungen liber die Schilddriise," in 

 Froriep's "N. Notiz." Bd. XL., p. 193; and Panagiotides, "De gland, 

 thyreoideee structura penitiori," Diss. Berol., 1847; A. Ecker, "Ver- 

 such einer Anatomic der primitiven Formen des Kropfes, &c.," in 

 "Henle and Pfeuffer's Zeitschrift," f. rat. Mod. VI., Bd., p. 123, and 

 Article " Blood-vascular glands," in Wagner's " Handw. cl. Physiol." 

 III.; Rokitansky, in " Zeitsch. d. Wiener Aerzte," 1847, and " Zur 

 Anatomic des Kropfes," in " Dcnkschriften der kaiserl. Akad. zu 

 Wien," Bd. L, Wien, 1849. 



OF THE THYMUS. 



182. The internal thoracic gland or thymus, also one of the so- 

 termed blood-vascular glands, is a bilobate, elongated, flattened organ, 

 broad iriferiorly, invested and united to the surrounding parts by a lax 

 connective tissue. Larger lobules, measuring on the average 2-5 lines, 

 and of a rounded, oval, or pyriform shape, though for the most part 

 flattened figure, are very distinctly apparent, even on superficial in- 

 spection ; these, although pretty closely approximated, are still united 

 merely by a yielding connective tissue, and may be separated without 

 difficulty. If these lobules be traced from without inwards, it is easily 

 perceived that they have no further mutual connection, although they 

 are invariably attached by a more slender portion, to a canal, which 

 traverses the interior of the gland, and is, in general, spirally convo- 

 luted, though not quite regularly so. When this canal, normally J-1J 

 lines in diameter, is opened, there are found on its inner surface a great 

 number of oval fissures or apertures, each of which leads to a lobule and 

 constitutes the outlet of a cavity contained in it. The resemblance of 

 this canal of the thymus and of the closely approximated lobules open- 

 ing into it, to the excretory duct and the lobules of a true gland, is still 

 further heightened by the circumstance, that the lobules are composed 

 of smaller, also hollow subdivisions and the latter of rounded cor- 

 puscles, 1-5-1-3 of a line in size, like gland-vesicles, the gland-granules 

 (acini of authors), which may be recognized even on the exterior, and, 

 from their polygonal shape, give the surface of the lobules a delicate 

 mosaic aspect, not unlike that of the lungs. These gland-granules, 

 however, are not vesicles at all, such as the air-cells, which, among the 



