412 THE SPLEEN AND THYMUS. 



occasionally found, and, if the cysts are large or numerous, may cause 

 more or less extensive atrophy of the organ. 



Various forms of bacteria have been found in the spleen. The pyo- 

 genie cocci have been found in pyaemia, small-pox, ulcerative endocardi- 

 tis, diphtheria, and under other conditions. The Bacillus anthracis oc- 

 curs here in anthrax ; the Bacillus tuberculosis in tuberculous inflammation ; 

 and typhoid bacilli in typhoid fever. Spirochsete Obermeieri may be pres* 

 ent in relapsing fever. 



The Thymus. 



MALFORMATION AND HYPERTROPHY. 



Small accessory tliymus glands are occasionally found near the thyroid. 



It is usual for the development of the thymus to reach its height in the early years 

 of life. It then undergoes involution or atrophy, losing its epithelial characters and 

 becoming largely composed of lymphoid cells. It is finally represented in old age by a 

 small mass of fat tissue. Occasionally, however, the thymus persists until youth or 

 middle age. ' Furthermore, it may become enlarged so-called hypertropJiy of the thymus. 

 The enlargement is, however, due to an hyperplasia rather than hypertrophy: the new- 

 formed tissue may present a more or less marked lobulated or glandular appearance. 

 This new formed tissue, according to the studies of Sultan and Lochte. may be largely 

 composed of lymphoid cells, or of larger polyhedral cells, so-called "epithelioid " cells. 8 

 Focal necroses have been recorded in diphtheria. 



HAEMORRHAGE. 



Small, and sometimes large, haemorrhages are occasionally seen in the 

 thymus of young children as the result of venous congestion in asphyxia, 

 poisoning, etc. They may also occur in the haemorrhagic diathesis. 



INFLAMMATION. 



Suppurative inflammation of the thymus is of occasional occurrence, 

 and is usually secondary to a similar inflammatory process in some other 

 part of the body. Tuberculous and syphilitic lesions of the thymus are 

 described, but are rare. 



TUMORS. 



Sarcoma is the most common tumor ; Angioma, Endothelioma, and Der- 

 moid Tumors are recorded. 



1 For the significance of a persistent thymus in certain cases of sudden death, see 

 Norton, Phila. Med. Jour., vol. i., p. 249, 1898, bibl. ; also ref. to Ewino, p. 49. On the 

 relationship of hyperplasia in a persistent thymus to Hodgkin's disease, consult Brigidi 

 and Piccoli, Zieg'ler's Beitr. z. path. Anat., etc., Bd. xiv., p. 388. 



2 See Lochte, Centbl. f. allg. Path. u. path. Anat., Bd. x., p. 1, bibl 



