VARIETIES OF INFLAMMATION DUE TO CAUSATION. 17 



the process of inflammation, viz., the altered state of the vessels, 

 from the phenomena which accompany it, and the textural 

 germination which it produces, its characters will appear to us 

 to present very slight variation, yet the visible results by which 

 it manifests itself differ widely in different cases. It is there- 

 fore necessary, in order to complete the present subject, to con- 

 sider in what degree these differences correspond to differences 

 in the causes which produce them. 



" Vesication. — If a hot iron is applied to the skin at a sufficient 

 temperature, it at once destroys its vitality. If the temperature 

 be a little below that which is necessary to produce this result, 

 the blood contained in the vessels coagulates, and the tissue 

 eventually dies. At a still lower temperature the skin retains 

 its vitality, but blisters are formed at or around the injured part. 



" If the mesentery of a guinea-pig is touched with a heated 

 surface, and the effect observed under the microscope, it is found 

 that stasis is produced which is co-extensive with the surface of 

 contact. It is tolerably certain that in like manner, in vesica- 

 tion of the skin by heat, the circulation of the heated part is 

 abruptly brought to a standstill. As, outside of the area of 

 stagnation, it goes on at first with unabated then with increased 

 vigour, while the walls of the capillaries are probably acted 

 upon by the heat in such a manner as to render them more 

 permeable, we can readily understand how it happens that 

 liquor sanguinis is exuded more rapidly and more abundantly 

 than in ordinary inflammations. From the researches of Dr. 

 Samuel of Konigsberg it seems probable that the effects of 

 liquid vesicants agree with those of heat in all the respects 

 which have been referred to; so that the peculiarity of the 

 mode of action of vesicant agents in general, would seem to lie 

 in its suddenness, and in the faculty which they possess of at 

 once producing those changes in the capillary wall which in ordi- 

 nary inflammation require a longer time and a more gradual 

 process for their production. In this way the exudation of 

 liquor sanguinis, instead of being deferred until the slowing 

 of the circulation has commenced, begins immediately, and, 

 favoured by the primary arterial afflux, and the increased intra- 

 vascular pressure consequent on the sudden capillary obstruc- 

 tion, is so abundant that the liquid collects in blisters. 



" Melation letween injlammation and the reparative process, — 



