COS (i. Jl. |.|;i':\V AND W. DM MORGAN. 



tissue. It seems that iu these cases bacteria must have 

 entered througli the drill-hole, and, travelling- between the 

 agar and muscle, have caused an intliiiniiiatury reaction. In 

 one other case, in which the hole had not come unsealed, in- 

 flammation and formation of fibrous tissue occurred, but as 

 this only took place once out of twenty-six implantations made 

 with sterile agar, it is probable either that the sealing-wax 

 plug leaked at the edges or that bacteria found their way in 

 when the agar Avas introduced. 



Summary ov Results. 



Our experiments show that the implantation of a tissue, 

 such as that forming the gills, accompanied by the bacteria 

 which adhere to it, produces an intense inflammatory reaction. 

 This is characterised by the active migration of blood- 

 corpuscles, which form a plasmodial mass around the im- 

 planted tissue, shutting it off from the general circulation. 

 This protective layer is gradually removed by phagocytosis 

 and autolysis, and at the same time the gill-tissue is invaded 

 and removed by phagocytes. While this is going on, rapid 

 amitotic division of the fibroblasts in the neijflibourhood 

 occurs ; they lose the typical spindle-shape of the nuclei, and 

 the new-formed cells consist of rounded or oval nuclei, with a 

 scarcely perceptible amount of cytoplasm. These rounded 

 cells migrate towards the implanted tissue, and arrange 

 themselves in layers around it, the nuclei become elongated, 

 and the proportion of cytoplasm increases. Finally, a layer of 

 typical "scar " fibrous tissue is formed, enclosing the chitinous 

 skeletons of the gill-bars. 



In the case of the implantation of digestive gland tissue a 

 similar protective layer of agglutinated corpuscles is formed, 

 but this is continually dissolved up and reformed, as the 

 sphere of action of the enzymes in the cells of the digestive 

 gland extends. All the muscle-fibres within this protective 

 layer soon lose their striation, swell, and are partially dis- 

 solved, presumably by the digestive enzymes. The fact that 



