SURGICAL COMPLICATIONS AND SEQUELS OF FEVERS. 35 



Although the precise factors in determining the thrombosis 

 in any individual case may be somewhat doubtful, as also why 

 it is frequent in one epidemic and rare in another, apparently 

 frequent in Germany and rare in Britain, and especially in the 

 United States, yet three causes clearly exist which may vary 

 inter ae in producing the result: 1, the altered blood; 2, the 

 weakened heart ; and 3, the mechanical difficulties in carrying 

 on the circulation, especially in distant parts. 



That the blood is profoundly altered, and probably has an 

 increased coagulability, is conceded. In some cases even air is 

 found in the veins, as noted by Crisp^ and Lebert.^ That every 

 such change, besides its depressing effect upon the nutrition, 

 and therefore upon the vitality of the tissues themselves, would 

 interfere more or less with its circulation, and consequently 

 predispose to thrombosis, is most probable. But when we 

 look at the seat of the cases of gnngrene of both varieties 

 which are under consideration, I think the conclusion is 

 inevitable, that the last two causes are the more immediately 

 determining factors. 



The heart, as Stokes showed, is softened in its texture, and 

 therefore weak. Hayem (see bibliog.) has shown that myo- 

 carditis is extremelj^ frequent, and not rarely involves the 

 endocardium. From the sixth to the fourteenth day is its 

 weakest period, and not onl3' is the general force of tlie circu- 

 lation diminished at this time, but all the blood not being 

 squeezed out of its cavity, clots may form in the heart, and 

 then, or at a later period, when the heart regains somewhat of 

 its force, be washed into the circulation and lodge as emboli. 

 Such seems to have been the origin of tlie clot in a remarkable 

 case related by Patry.^ A decolorized adherent embolus was 



' Dis. Bloodvessels, p. 18. 



2 Prag. Vierteljahr. 1858, i. 33. Moorehearl, Trans. Med. and Pbys. 

 Soc. Bombay, 1843, p. 6S, also reports a case. 



3 Archiv, (jl6n,, 18G3, i. 144. 



