384 ANDEE CEOTTI 



In 1858, Friedleben reported that the thymus in acute infections ber 

 comes, on the average, about three times larger than normally, whereas 

 in chronic conditions it undergoes a marked atrophy. 



In 1888, Jacobi made a microscopical examination of nine cases who 

 died from acute infections such as diphtheria, bronchopneumonia, and 

 in two cases only did he find necrobiotic changes in the lymphocytes. 



In 1894, O. Hausen reported observations obtained from 16 postmor- 

 tems, the cause of death being diphtheria. He found an enlarged thymus 

 in each case. 



In 1894, Mettenheimer examined 13 cases of diphtheria and 5 cases 

 of scarlet fever and came to the conclusion that in acute infections 

 the thymus undergoes involution instead of hyperplasia. Microscopically, 

 he found hyperemia of the thymus and did not find the same degenerative 

 changes of the cells, such as described by Jacobi. 



In 1900, Eoger and Ghika made some experimental researches to see 

 how the thymus reacted toward infections and at the same time examined 

 the thymi of patients dying from acute infectious diseases such as scarlet 

 fever, varioloid, diphtheria, erysipelas, pertussis, tuberculosis and syphilis. 

 Experimentally, by injecting in guinea-pigs virulent cultures of strep- 

 tococci, staphylococci, colon bacilli, and Loffler bacilli, they were able to 

 produce the same pathological changes as observed in acute infections, i. e. 

 hyperplasia of the thymus, congestion, punctate and subcapsular and 

 intracapsular hemorrhages. Microscopically, they found the walls of the 

 blood vessels infiltrated with leukocytes and showing some hemorrhagic 

 foci. The lymphocytes were quite numerous especially in the medullary 

 portions. Mono- and polynuclears, eosinophiles, neutrophiles, mast cells 

 and giant cells were observed. Hassall's corpuscles were increased in 

 size and number and showed some retrogressive changes. 



In 1901, Magni made cultures of the thymus of children who died from 

 acute infections and was able to obtain positive cultures. It is his opinion 

 that the thymus is more frequently invaded by microbes than the liver, 

 spleen, mesentery, etc. 



In 1903, Francesconi studied experimentally the influence of microbic 

 infections upon the thymus of guinea pigs and found that the gland be- 

 comes hyperplastic, that the lymphoid elements, especially the medullary 

 portions, become markedly increased, showing karyolytic changes, and 

 that the endothelium of the blood vessels is swollen and the connective 

 tissue is infiltrated with leukocytes. 



In 1904, Mensi repeated the same experiments and found that in 11 

 cases out of 26, the bacteriological examination of the thymus was positive. 

 In 22 out of 26 cases the Hassall's corpuscles were markedly increased 

 in size and number and the eosinophiles were also increased. 



Bracci, in 1904, studied the relation of the thymus to infections and 

 observed that the HassalPs corpuscles underwent degeneration and that 



