242 DISTURBANCES OF CIRCULATION 



decrease in the alkalinity of the blood in leucocytosis, or when 

 virulent bacteria were introduced into the blood. Awerbach l 

 claims that in severe high fevers the bactericidal effect of the 

 blood alkalinity is increased (see also " Passive Congestion " 

 for further discussion concerning the relation of alkalinity to 

 bactericidal power). 



HEMORRHAGE 



Hemorrhages result from an altered condition in the vessel- 

 walls, which may be due either to trauma or to chemical inju- 

 ries. Of the chemical agencies causing hemorrhages, bacterial 

 products are the most important practically, but many poisons, 

 such as phosphorus, formalin, phytotoxins (ricin, abrin, and 

 crotin), and zootoxins (snake venoms) cause numerous and 

 abundant hemorrhages. Formerly, the tendency was to ascribe 

 hemorrhages from the above causes to mechanical injury of the 

 vessels by thrombi, or by emboli of agglutinated corpuscles, but 

 the work of Flexner 2 has shown that venoms cause hemor- 

 rhages by injuring the capillary walls, so that actual rents are 

 produced by the intravascular pressure, and it seems highly 

 probable that hemorrhages are produced by other chemical sub- 

 stances in a similar way. We may, therefore, refer such hem- 

 orrhages to an endotheliotoxic action of the poison, or to a solvent 

 effect upon the intercellular cement substance. In the case of 

 ordinary chemical poisons the endotheliotoxic action is not spe- 

 cific, but with some of the toxins it seems to be quite so ; for 

 example, rattlesnake venom contains an endotheliotoxic sub- 

 stance (hemorrhagiTi), which seems to be a specific poison for 

 endothelium, and which is the most dangerous constituent of 

 the venom. If we immunize animals against tissues containing 

 much endothelium (e. g. y lymph-glands), their serum w r ill be 

 found to contain endotheliotoxins, so that when this serum is 

 injected subcutaneously into a susceptible animal, large local 

 hemorrhages result ; if injected into the peritoneal cavity, there 

 results marked desquamation of the endothelial cells, which soon 

 undergo degenerative changes (Ricketts 3 ). It is quite probable 

 that the bacterial poisons that cause marked hemorrhagic mani- 

 festations likewise contain endotheliotoxins, although this matter 

 does not seem to have been investigated. 



Even hemorrhage by diapedesis seems to be due to, or at least 

 associated with, chemical changes in the capillary walls, for 



1 Med. Obosrenije, 1903, p. 596. 



2 Univ. of Penn. Med. Bull., 1902 (15), 355. 



'Trans. Chicago Path. Soc., 1902 (5), 181. 



