440 M. AEMAND RUFFER. 



round or oval form of typical nuclei. During their formation 

 the protoplasm of the epithelioid cell increases in size and 

 takes the characteristic dimensions of a giant- cell. This process 

 is not actually caused by the presence of the tubercle bacilli, 

 for it occurs in empty cells as well as in cells containing bacilli. 

 Most of the bacilli contained in epithelioid cells appear to 

 be quite healthy, but in the giant-cells degenerated micro- 

 organisms are frequently met with. Many bacilli contained 

 in the giant-cells are of a faint rose colour, remain unstained, 

 or take up the blue colour only ; whilst in a further stage of 

 degeneration they become surrounded by an aureole resembling 

 the clear space found around the pneumococcus of Friedlander. 

 The micro-organisms become paler, stain less deeply or may 

 even not stain at all, whilst their outlines become clearly 

 defined. Finally they seem to disappear, but outlines of the 

 surrounding yellowish capsule become more defined and 

 sausage-shaped. These sausage-shaped bodies join, fuse 

 together, lose their shape, and finally form an amber-coloured 

 mass, which in no way resembles the bacilli from which it is 

 derived. This process, therefore, is not a true digestive pro- 

 cess, since the cells convert the bacilli into a solid resistent 

 mass instead of liquefying them ; it resembles rather the 

 encapsulation of some Infusoria. 



Similar forms of degeneration are to be met with in the 

 giant-cells of tuberculous rabbits.^ But although the writer 

 has not unfrequently observed the formation of giant-cells by 

 indirect division of the nucleus of epithelioid cells, it is quite 

 clear that in the rabbit, guinea-pig, and man the giant-cells 

 arise from the fusion of two or more epithelioid cells without 

 any apparent transformation in the nucleus. 



Lately fresh evidence has been accumulating to prove that 

 the function of giant-ceils formed in pathological new growths 

 is identical with that of giant-cells found in the normal healthy 

 body. Soudakewitch^ has shown that the giant-cells of lupus 

 iu man feed on the neighbouring diseased tissue, and digest 



' Metschnikoff, loc. cit., and Armaiid Ruffer, unpublished observations. 

 * tSoudakewitch, ' Vircliow's Arcliiv,' v. cxv, p. 204. 



