114 ANATOMY FOR NUKSES. [CHAP. X. 



with white corpuscles. At the same time the lymph not only 

 increases in amount, but changes somewhat in its chemical 

 characters ; it becomes more distinctly and readily coagulable, 

 and is sometimes spoken of as " exudation fluid." This change 

 of the lymph with the increased quantity, together with the 

 dilated crowded condition of the blood-vessels, gives rise to the 

 swelling which is one of the features of inflammation. 



If the inflammation now passes away, the white corpuscles 

 cease to emigrate, cease to stick so steadily to the sides of the 

 vessels, the stream of blood quickens again, the vessels regain 

 their ordinary calibre, and a normal circulation is re-established. 

 But this inflammatory condition, instead of passing off, may go 

 on to a further stage ; and, if this is the case, more and more 

 white corpuscles, arrested in their passage, crowd and block the 

 channels, so that, though the vessels remain dilated, the stream 

 becomes slower and slower, until at last it stops altogether, and 

 stagnation or " stasis " sets in. The red corpuscles, in this con- 

 dition of things, are driven in among the white corpuscles, the 

 vessels are filled and distended with a mingled mass of red and 

 white corpuscles, and it may now be observed that the red cor- 

 puscles also begin to find their way through the distended and 

 altered walls of the capillaries into the lymph spaces outside. 

 This is called the diapedesis of the red corpuscles. 



This stagnation stage of inflammation may be the beginning 

 of further mischief and of death to the inflamed tissue, but it, 

 too, may, like the earlier stages, pass away. 



General summary of the circulation. The perfect circulation 

 of the blood is dependent upon certain factors, the chief of 

 which are : (1) the character of the heart-beat ; (2) the con- 

 traction and relaxation of the minute arteries ; (3) the elas- 

 ticity and extensibility of the arterial walls ; (4) the perfect 

 adjustment of the valves. 



The character of the heart-beat is mainly determined by the 

 condition of its muscular substance, and any interference with 

 the nutrition of the heart leading to degeneration of its mus- 

 cular walls very seriously affects the heart's action. 



The contraction and relaxation of the smaller arteries is 

 under the influence of the nervous system, the particular fibres 

 distributed to them being known as the vaso-motor nerves. 

 The widening and narrowing of these arteries not only affects 



