TUBERCULOSIS. 227 



plasm of the cells affected takes on a hyaline character, 

 and seems abnormally viscid, so that contiguous cells 

 have a tendency to become partially confluent. The 

 chromatin of their nuclei becomes dissolved in the nu- 

 clear juice and gives stained nuclei a pale but homo- 

 geneous appearance. Sometimes this nuclear change is 

 only observed very late. As the necrosis advances the 

 contiguous cells flow together and form large protoplas- 

 mic masses giant-cells which contain as many nuclei 

 as there were component cells. It may be that these 

 nuclei multiply by karyokinesis after the protoplasmic 

 coalescence, but only one observer, Baumgarten, has 

 found signs of this process in giant-cells. While these 

 changes are in progress in the cells of the primary focus, 

 the leucocytes may collect in such numbers as to obscure 

 them and make themselves appear to constitute the prim- 

 itive cells. When the irritant substance is produced in 

 considerable quantities, the most delicate cells die first ; 

 and it is not infrequent to find a tubercle rich in leuco- 

 cytes suddenly showing degeneration of these cells, with 

 recurring prominence of the original epithelioid cells. 



It has been taught by some that the giant-cells are 

 produced by the union of the leucocytes, but a careful 

 observation of the role played by these cells will convince 

 one that such an origin for these monstrous cells must be 

 very rare. 



Giant-cells are not always produced, for sometimes the 

 necrotic changes are so violent and widespread as to con- 

 vert the whole cellular mass into a granular detritus of 

 unrecognizable fragments. 



Tubercles are constantly avascular, as would be ex- 

 pected of a process which is a combination of progressive 

 irritation and necrosis. The avascularity may be a fac- 

 tor in the necrosis of the larger tuberculous masses, but 

 it plays no part in the degeneration of the smallest tuber- 

 cles, which is purely toxic. 



Tubercles may be developed in any tissue and in any 

 organ. In whatever situation they occur, space is occu- 



