274 GENERAL ANATOMY. 



which the termination and communications of the vessels 

 aflfect particular dispositions. Hensinger has given to them 

 the name of parenchymatous tissue. 



Their texture results from the union of several other tissues. 

 They are formed of modified cellular tissue, of blood vessels 

 and lymphatics, and of nerves; the whole inclosed in an enve- 

 lope, which send prolongations into the interior. They are 

 all situated in the course of the lymphatic and venous circu- 

 lation, and seem to be destined to make the absorbed sub- 

 stances undergo an elaboration, and to prepare their assimila- 

 tion; they thus appear to be in a kind of antagonism to the 

 true glands or the organs of excretion. The vascular ganglia 

 differ from each other in the quantity and the species of tissue 

 of which their mass is formed, in the proportion of vessels 

 and nerves, and in the mode of communication of the vessels. 



404. The adenoid ganglia may be distinguished into two 

 kinds: 1st, the lymphatic glands or ganglia; and 2dly, the 

 ganglia of the blood vessels, which are the thyroid gland, the 

 thymus, the surrenal capsules, and the spleen. 



The former of these will be described along with the lym- 

 phatic vessels, (sect, iv.) The others, which form a less na- 

 tural group, belong principally to special anatomy. They have, 

 however, some general characters. The ganglions of the 

 blood vessels* are larger and much less numerous than the 

 lymphatic ganglia. They are of a brownish-red colour, glo- 

 bular and granular. They present internally distinct cavities, 

 filled with a fluid, but little ramified and closed on all sides. 

 It was believed, at divers epochs, that excretory ducts had 

 been discovered in them, but these supposed discoveries have 

 not been confirmed. These ganglia are so intimately con- 

 nected with the blood vessels and lymphatics, and especially 

 with the thoracic duct, that they have been supposed, with 



* Boeckler, de Functionibus glanduhs thyreoidx, thymi, atque glandul 

 9upraren. t fcfc. Argentor. 1753. Hecker, iiber die verrichtung der kleinsten 

 scklagaden und einger cms einem gewebe der feinsten gefasse bestehenden ein- 

 geweide, der schild-und brust-druse, der milzes, der nebennieren und nachge- 

 burt, Erfurt, 1790. 



