18 Mr. J. C. Mottram and Dr. S. E,uss. Susceptibility and 



globules and cells. Lymphocytes form the rest of the cellular elements, they 

 are more or less evenly distributed throughout the tissue, being a little more 

 numerous close to the graft. Lymphatics, capillaries, and small blood-vessels 

 are scattered through the tissue ; in many cases their endothelial cells are 

 seen to be dividing (vide fig. 12). 



The whole of the inoculated sarcoma emulsion presents degenerative 

 changes, except for a few cells deep just within the cleft, where some healthy 

 sarcoma cells are to be seen. Polymorphonuclear leucocytes are everywhere 

 scattered between the sarcoma cells ; the groundwork consists of a structure- 

 less granular material. The nuclei of the sarcoma cells are shrunken and 

 their chromatin irregularly distributed. The whole nucleus often stains very 

 deeply, whilst the protoplasm is pale and vacuolated. 



(b) Forty-eight Hours after Inoculation {vide fig. 13). — The reaction tissue 

 now measures 1 to 2 mm. in width, being narrower than in the 24-hour 

 specimen. The groundwork consists of a close network of fibrous material, 

 with only small, narrow hyaline masses in its meshes. Through this ground- 

 work the cells have the following arrangement : Near the emulsion, but 

 outside the cleft, are to be seen many healthy sarcoma cells, some dividing ; 

 mixed with them are a few polymorphonuclear leucocytes. Lymphocytes 

 are scattered through the tissue ; they are more numerous around the blood- 

 vessels than elsewhere, and more numerous than in the 24-hour specimens. 



This appearance of greater numbers may be due to their being more 

 concentrated, owing to the shrinkage in width of the reaction tissue. At 

 the periphery of the reaction tissue, the cellular elements are as in the 

 24-hour specimen, except that a few plasma-cells are to be seen near the 

 outlying blood-vessels. The blood-vessels are more numerous, and are to be 

 seen close to the sarcoma cells, external to the cleft. The sarcoma cells 

 inside the cleft present more advanced degenerative changes than in the 

 24-hour specimen ; only a few healthy cells are to be seen close to the 

 margin. 



(c) Seventy-two Hours after Inoculation {vide fig. 14). — Immediately 

 outside the cleft, closely packed sarcoma cells now form a band of growth 

 encircling the originally inoculated material, which now consists of structure- 

 less cell-debris. Among the sarcoma cells are a small number of lymphocytes, 

 numerous blood-vessels, and lymphatics. Outside this band of growth the 

 reaction tissue is similar to that seen in the 48 -hour specimen, except that 

 blood-vessels are more numerous and in places closely packed together, 

 while lymphocytes and plasma-cells are less numerous. 



(d) Four to Seven Days after Inoculation. — The reaction tissue of the host 

 shows no change. As the sarcoma invades the reaction tissue next to it. 



