294 INFLAMMATION. [BOOK i. 



stasis may by irritants be induced in which oil-globules play the 

 part of corpuscles, and by their aggregation bring about an arrest 

 of the flow. 



We are led to conclude that there exist in health certain 

 relations between the blood on the one hand, and the walls of the 

 vessels on the other, by which the tendency of the corpuscles to 

 adhere to the blood vessels is kept within certain limits ; these 

 relations consequently determine the normal flow, with its axial 

 stream and peripheral zone, and the normal amount of peripheral 

 resistance; in inflammation, these relations, in a manner we 

 cannot as yet fully explain, are disturbed so that the tendency 

 of the corpuscles to adhere to the sides of the vessels is largely 

 and progressively increased. Hence the tarrying of the corpuscles 

 in spite of the widening of their path, and finally their agglomera- 

 tion and fusion in the distended channels. 



The changes occurring in the vascular walls at the same time 

 also modify the passage from the blood to the tissue of the fluid 

 parts of the blood, the lymph of inflamed areas being more 

 abundant and richer in proteids than normal lymph. There is a 

 greater outflow from the interior of the blood vessel into the 

 lymph spaces outside, and, indeed, it has been urged that this, 

 carrying the blood corpuscles with it, mechanically promotes the 

 gathering of the white corpuscles at the sides of the vessel and 

 their subsequent passage through the walls. 



We must not, however, pursue this subject of inflammation any 

 further. We have said enough to shew that the peripheral re- 

 sistance (and consequently all that depends on that peripheral 

 resistance) is not wholly determined by the varying width of the 

 minute passages, but is also dependent on the vital condition of 

 the tissue of which the walls of the passages form a part. When 

 the tissue is in health, a certain resistance is offered to the 

 passage of blood through the capillaries and other minute vessels, 

 and the whole vascular mechanism is adapted to overcome this 

 resistance to such an extent that a normal circulation can take 

 place. When the tissue becomes affected, the disturbance of the 

 relations between the tissue and the blood may so augment the re- 

 sistance that the passage of the blood becomes, as in inflammation, 

 difficult, or, as in stasis, impossible. And it is quite open to us to 

 suppose that under certain circumstances the reverse of the above 

 may occur in this or that area, that conditions may arise in which 

 the resistance is lowered below the normal, and the circulation in 

 the area quickened. Thus the vital condition of the tissue becomes 

 a factor in the maintenance of the circulation ; and it is possible, 

 though not yet proved, that these vital conditions are directly 

 under the dominion of the nervous system. 



163. Changes in the peripheral resistance may also be 

 brought about by changes in the character of the blood, especially 

 by changes in the relative amount of gases present. When a 



