HYPEREMTA 261 



products accumulate, and possibly noxious products of metab- 

 olism are formed under lack of oxidation ; either from these 

 causes or solely from pressure and lack of nutrition there is a 

 tendency to atrophy of the more specialized parenchymatous 

 cells, and a proliferation of connective tissues. The atrophy of 

 parenchyma is seen particularly in the liver, the increase of 

 connective tissue in the spleen. 1 In the kidney neither atrophy 

 nor stroma proliferations are pronounced, but the renal function 

 is greatly impaired, since it depends upon the amount and quality 

 of the blood brought to the kidney. Whether connective-tissue 

 proliferation in hyperemia depends upon overnutrition or upon 

 irritation by waste-products, or is compensatory to parenchyma- 

 tous atrophy, may be looked upon as still an open question. 

 Probably only the first two factors apply to the connective-tissue 

 growth observed in the congested spleen, the clubbing of the 

 fingers in congenital heart disease, or the thickening of the sub- 

 cutaneous tissues in passive congestion of the lower extremities. 

 The edema of passive congestion seems to result partly from 

 mechanical forces and partly from the high osmotic pressure that 

 develops in the underoxygenated tissues (see "Edema," Chap. xii). 

 Changes in the Blood. Venous blood differs from 

 arterial, not only in its increased load of CO 2 and other waste- 

 products, but also in other ways. Venous blood generally clots 

 less readily than arterial blood. 2 It contains more diffusible 

 alkali because the CO 2 combines with and tears away part of 

 the bases that are held by the proteids, especially in the cor- 

 puscles, and so alkaline carbonates are formed and enter the 

 plasma. Blood from the jugular vein on this account contains 

 20-25 per cent, more diffusible alkali than carotid blood (Ham- 

 burger 3 ). Since the bactericidal power of the blood has been 

 shown to increase directly with the alkalinity, this property 

 may be of importance in pathology. For example, the relative 

 infrequency of infections in the right side of the heart may not 

 depend solely upon lessened liability to endocardial damage, as 

 generally considered, but is possibly due in part to the greater 

 bactericidal power of venous blood. The same property prob- 

 ably explains the favorable results obtained in the treatment of 

 local infections by artificially produced passive congestion. 4 



1 See Christian, Jour. Amer. Med. Assoc., 1905 (45), 1615. 



2 Vierordt (Arch. f. Heilk., 1878 (19), 193) found coagulation faster in the 

 blood in passive congestion than in normal venous blood ; but Hasebrock (Zeit. 

 f. Biol., 1882 (18), 41) found that if the stasis is protracted, the coagulation 

 becomes delayed because of the excess of CO 2 . 



3 Virchow's Arch., 1899 (156), 329; also, "Osmotischer Druck und lonen- 

 lehre," 1902, p. 280. 



4 See Bier, " Hyperaemie als Heilmittel," Leipsic, 1903. 



