Inflammation. Phlogosis. Phlegmasia. 43 



Finally they separate, together with the cell protoplasm, forming 

 two daughter cells. 



This cell proliferation under the action of an irritant is com- 

 mon to the vegetable kingdom in which galls and tumors are 

 formed in this way. It is a remarkable feature of these multi- 

 plying cells that they not only lose their power of developing the 

 tissue in which they formerly lay, and have all their vital powers 

 devoted to proUferation, but they acquire the amoeboid power of 

 their ancestors, the embryonic cells, which they further resemble 

 in size. Indeed these cells are freely spoken of as embryonal 

 cells, and the tissue formed by their massing together as embry- 

 onal tissue, and there is a widespread impression that they revert 

 entirely to the form and characters of the embryonic cell. In 

 some respects, however, they are unlike. The modified tissue- 

 cell of inflammation presents a nucleus of horseshoe outline, or 

 after division of the nuclei they together retain this semi-circular 

 outline ; it has the power of actively digesting the adjacent tis- 

 sues as the embryonic cells do not, and again it does not possess 

 the power of differentiation into widely different tissues as does 

 the early embryonic cell. It may be called a reversion, in the 

 direction of the embryonic cell, however, since it reacquires a 

 number of its functions. 



Migration of white blood cells. This is another, and in 

 vascular tissues the main source of the great cell accumulation 

 in the inflamed tissue. This process was observed by Waller in 

 1846, but was given its true importance through the later obser- 

 vations of Cohnheim. The migration takes place through the 

 walls of the capillaries and veins only, and the migrating cells 

 are largely of the poly-nuclear variety of leucocytes. These re- 

 maining adherent to the inner wall of the blood vessel may be 

 seen to have a small portion of their substance projected through 

 the wall and appearing as a small buttonlike projection on the 

 outer side. This gradually increases, while the remaining por- 

 tion of the cell on the inner side of the wall correspondingly de- 

 creases until the whole cell is lodged in the tissue outside the 

 vascular wall. The time occupied in passing through is very 

 varied. It may be wholly accomplished in half a minute, and 

 again hours may be required for the complete passage of a single 

 leucocyte. The explanation of this migration has been sought 



