444 M. ARMAND RUFFEE. 



and destroy the smaller ones, so do the macrophages met with 

 in actinomycosis destroy the microphages. It is easy to find 

 such macrophages containing one, two, or as many as five or 

 six microphages in various stages of degeneration (figs. L, 

 m, and M, h,j, k, I; also fig. H). Several epithelioid cells may 

 then coalesce and form a giant-cell (fig. H, a, b, c, d, e) ; 

 but I have never seen division of nuclei as in the epithelioid 

 cells of Spermophilus guttatus. 



Near the growing edge of the tumour each rosette is sur- 

 rounded by a layer of epithelioid and giant cells, forming a 

 regular palisade around the nodule. The nuclei of such cells 

 are always placed at the pole situated away from the parasite. 

 The epithelioid cells in other places penetrate into the rosette 

 of actinomycosis and take into their interior huge bunches of. 

 these parasites (fig. F), which then undergo degeneration in the 

 interior of these cells. The giant-cells likewise often contain 

 masses of such parasites (fig. G). At the growing edge of the 

 tumour, however, giant-cells are few, and, as might be expected, 

 there is no formation of new connective tissue. 



In the parts of the tumour which are older, and therefore 

 harder and more fibrous, the appearances are very different. 

 The periphery of each nodule is surrounded by a dense capsule 

 of fibrous tissue. The epithelioid cells, however, take no part 

 in the formation of this fibrous tissue, for in no case could I 

 see appearances justifying such an assumption. On the 

 contrary, the connective tissue is derived from small cells pos- 

 sessing a hard, darkly staining single nucleus. These cells 

 gradually elongate, the nucleus becomes oval and clearer at 

 the same time, until typical long spindle-shaped connective- 

 tissue cells are produced (fig. J). 



The appearances of the disease in a fibrous part of the 

 tumour are very different from those seen near the growing 

 edge. The older parts generally contain a large number of 

 epithelioid cells and giant-cells, holding in their interior 

 bunches of actinomycosis, which often show signs of degenera- 

 tion. Instead of staining of a dark purple colour with geu- 

 tiau-violet the parasites do not stain at all, but become con- 



