386 ANDRE CROTTI 



j 



Furthermore, in examining the relation of the thymus to infectious 

 diseases such as acute anterior poliomyelitis, measles, scarlet fever, per- 

 tussis, typhus, typhoid, etc., Hammar, in 1918, observed that the thymus 

 in a general way showed an increase in size and number of the HassalFs 

 corpuscles. In diseases of long standing such as chronic tuberculosis, etc., 

 the thymus underwent an involution, but no increase in size and number 

 of the Hassall's corpuscles was observed. The same is also true in the case 

 of hunger. 



In conclusion, we may say that the thymus reacts towards infectious 

 disease mostly by an increased blood supply, by hyperplasia of the thymic 

 elements, and by hyperplastic changes taking place in the Hassall's cor- 

 puscles. In some instances, however, pathological involution, instead of 

 hyperplasia, takes place. 



Sclerosis of the Thymus. In certain cases of malnutrition, of syphilis, 

 and of tuberculosis, the thymus undergoes a process simikr to the one 

 observed in atrophic cirrhosis of the liver and kidney. There, too, as in 

 the latter conditions, we have a process of connective tissue formation, 

 gradual in character, involving the cortical substance first and the medul- 

 lary portion of the thymus afterwards. In the terminal stage all that 

 remains of the thymus is a small but hard mass involving the whole gland 

 and firmly attached to the neighboring tissues. This sclerosis of the 

 thymus in many respects resembles the one seen in the thyroid and called 

 "woody thyroiditis." In rare cases, as reported by Klose, the production 

 of connective tissue is so great that this author is inclined to regard these 

 cases as fibromata. 



Syphilis of the Thymus. Nothing is known of secondary syphilis 

 so far as the thymus is concerned. 



Tertiary syphilis has been found once in a while and is characterized 

 by gummata, which do not differ in any way from those seen in other 

 organs. 



In hereditary syphilis Paul DuBois, in 1850, described abscesses 

 known since in the literature as "DuBois abscesses." They are not ab- 

 scesses in the true sense of the word, but are due to the breaking down 

 of a syphilitic gnmma. Some pus is usually found. They always contain 

 a large amount of spirochetes. 



Chiari (a) (fr), in 1894, studying several of these so-called "DuBois 

 abscesses" in the new-born, found on microscopical examination that these 

 abscesses were surrounded by a capsule composed of several layers of cells 

 plainly keratohyalin in character. He concluded, therefore, that these 

 abscesses originated in previously existing cysts. The contents of these 

 cysts was composed of cells with large, clear nuclei, and small lymphoid 

 cells. The keratohyalin character of the cells led him to conclude that the 

 cyst took its origin primarily in a Hassall's corpuscle. 



Tuberculosis of the Thymus. Primary tuberculosis of the thymus is 



