324 DISTURBANCES OF CIRCULATION 



blood, even without injury to the vessel-walls."* Presumably the clot- 

 ting does not occur when the stream is rapid, because any fibrin- 

 ferment that may be liberated by injured leucocytes or endothelium 

 is swept away before fibrin can become attached to the vessel-wall; 

 or, according to Howell's hypothesis, because the current brings an 

 excess of antithrombin to the point where the thromboplastin is being 

 formed. Naturally, the combination of an injured vessel-wall, a slow 

 current, and a high coagulability offer the most favorable conditions, 

 and we owe to Welch the appreciation of the fact that in a large pro- 

 portion of all thrombi, even those caused by apparently purely me- 

 chanical agencies (e. g., cardiac incompetence), bacteria are present 

 and probably determine the injury to the vessel-walls and the libera- 

 tion of fibrin-ferment.'^'' We have previously referred to L. Loeb's 

 observations on the effect of bacteria in causing coagulation of the 

 blood. 



Hyalin thrombi are frequently the cause of extensive degenerative 

 lesions in the viscera, and although commonly formed of red corpuscles, 

 they do not stain at all like normal corpuscles, presumably because 

 a certain proportion of the hemoglobin has been altered or lost through 

 hemolysis. Of particular interest is their reaction to Weigert 's fibrin 

 stain, by which they often, but not always, stain intensely: a fact that 

 has been the cause of much confusion in earlier studies. Flexner '^^ 

 first appreciated the nature of these thrombi as originating from ag- 

 glutinated red corpuscles, although Klebs, Ziegler, and others had 

 earlier suggested that hyalin thrombi were formed from red corpus- 

 cles. Boxmeyer "^ independently arrived at the same conclusion as 

 Flexner, in studying hyalin thrombi as the cause of necrosis in the 

 liver of animals infected with the hog-cholera bacillus. Flexner pro- 

 duced hyalin thrombi by injecting eor]iuscles agglutinated by ricin, 

 or by injecting ricin itself, or hemolytic substances such as ether or 

 foreign serum. As the thrombi become old, the corpuscles lose their 

 form and color and produce the typical hyalin appearance. Pearce "- 

 proved conclusively the dependence of the thrombus formation upon 

 agglutination, for he secured the same results, including the liver ne- 

 crosis, by injecting specific agglutinating serums. He states that fib- 

 nn threads may occasionally be found at the periphery of the larger 

 thrombi, but never in the smaller ones. The tendency of the thrombi 

 to stain like fibrin by Weigert 's method is observed particularly when 

 the tissues have been hardened in Zenker's solution. It is extremely 

 probable, from Flexner 's observations, that in the thrombosis pro- 

 duced by injecting various toxic substances into the blood, the so- 

 bs Dietrich, Cent. f. Path. (Verhandl.) , 1912 (23), .372. 



53 Welch, Venous Thrombosis in Cardiac Disease, Trans. Assoc. Anier. Phys., 

 1900, vol. 15. 



«oJour. Med. Research, 1002 (S), .110. 



"Jour. :Med. Kesearcli, ino:{ (0), 140. 



"2 Jour. Med. Research, 1!)04 (12), 329; ih'uL, 1000 (14), .-)41. 



