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27 



the capillaries, and in tlie tenninal In'anrlies of the interlobular 

 arteries. They are seen in the glomerular capillaries, the atfercnt 

 and efferent vessels, the interlohular arteries, and the intertulnilar 

 capillaries of the cortex. In such cases we also find quite a numher 

 of vasa recta of the medulla obliterated. In favorable sections we 

 may occasionally be able to follow the thromi)Osis from a larger 

 artery into the smaller branches and into the capillaries. The 

 thrombi vary much in degree of density. We may encounter ])er- 

 fectly solid, heavy ones, which even in the thinner sections appear as 

 hyaline structureless masses, which have greatly extended the vessel 

 and stretched it, both in a transverse and in a longitudinal direction, 

 so that it appears very much like a sausage contained in a thin skin; 

 or, on the other hand, we may find tubular wall thrombi with open 

 lumina in the center, or a solid thrombus, which, however, does not 

 completely fill the vessel, but leaves a circular lumen between itself 

 and the vessel wall. We also see thrombi which are distinctly 

 fibrous in structure, being composed of longitudinally and reticu- 

 larly arranged filaments. Or again, we encounter thrombi made up 

 of a very loose reticulum. The vessel walls, as a rule, show no 

 appreciable morphologic changes. The intima and its endothelium 

 are well preserved, and in the small arteries we see well-preserved 

 muscle fibers. However, if the thrombi are quite solid and dense, 

 then the vessel walls generally show a minor degree of injury, and 

 their cellular structural elements can not be clearly distinguished. 

 In most of the cases in which we found hyaline thrombi in the 

 renal vessels, bacterial emboli were not encoimtcred. However, in 

 other instances, such emboli are present eitlicr as dense bacterial 

 masses or as loose groups of plague bacilli. In such cases in one 

 place in the section there may be seen a bacterial embolism and in 

 another a hyaline thrombosis, and occasionally one may encounter 

 thrombi and invading bacteria in the same area. But it is per- 

 fectly clear, as a careful examination will rev(>al, that the bacterial 

 invasion is not the cause of the thrombus formation, because the 

 latter, as a rule, occurs quite independently of the former. 

 Among our 31 cases there are instances with profound thrombosis 

 but without bacterial invasion of the kidneys, and on the other 

 hand, of extensive metastatic bacterial emboli without hyaline 

 thrombi. As a general rule, where we fiiul extensive hyaline 

 thrombosis in the primnrv bubo ami in tlir s[)leen, we also encounter 

 it in the kidnevs. 



