240 LECTURE X. 



particles are torn away by the blood as it streams by 

 (Fig. 71, 0- 



Through the vessel originally occluded no blood at all 

 flows ; in it the circulation is entirely interrupted : but 

 in the larger trunk through which the blood still con- 

 tinues its course, and into which only at intervals the 

 thrombus-plugs project, the stream of blood may detach 

 minute particles, hurry them away with it, and wedge 

 them tightly into the nearest system of arteries or capil- 

 laries. 



Thus we see, that as a rule all the thrombi at the pe- 

 riphery of the body produce secondary obstructions and 

 metastatic deposits in the lungs. I long entertained 

 doubts whether I ought to consider the metastatic inflam- 

 mations of the lungs one and all as embolical, because it 

 is very difficult to examine the vessels in the small me- 

 tastatic deposits, but I am continually becoming more 

 and more convinced of the necessity of regarding this 

 mode of origin as the rule. When a considerable num- 

 ber of cases are compared statistically, the result ob- 

 tained is that every time metastatic deposits occur, 

 thrombosis is also present in certain vessels. Quite re- 

 cently, for example, we have had a tolerably severe 

 epidemic of puerperal fever, and in this it was found 

 that, however manifold the forms the disease assumed, 

 yet all those cases which were accompanied by metas- 

 tases in the lungs, were also attended with thrombosis in 

 the region of the pelvis or in the lower extremities, whilst 

 in the inflammations of lymphatic vessels the pulmonary 

 metastases were wanting. Such statistical results carry 

 with them a certain amount of compulsory conviction, 

 even where strict anatomical proof is wanting. 



Into the pulmonary artery the introduced fragments of 

 thrombus of course penetrate to different depths accord- 

 Ing to their size. Usually a fragment of the kind sticks 



