ELEMORRHAGIC INFARCTION OF THE LUNG. 161 



Furthermore, we should remark that it is not in every hsemor- 

 rhagic infarction that an embolus, nor indeed any other source for 

 it, can be made out. In such cases the infarction probably comes 

 through rupture of larger vessels, arising in part from the pres- 

 sure of obstructive hypersemia in the lesser circulation, and in 

 part through fatty degeneration of some of the medium-sized and 

 smaller branches of the pulmonary artery. " Upon occurrence of 

 a rupture," says jRindfleisch, "the blood bores its way into a 

 neighboring bronchus with all the force of the abnormal pres- 

 sure then existing in the lesser circulation. Thence, by aspiration, 

 it is drawn into the corresponding lobule, filling it to the very 

 last vesicle. On the other hand, the blood also rises in the bron- 

 chus, and as the accumulation reaches the mouths of new bron- 

 chioles it is sucked into them. Coagulation of the extravasated 

 blood finally takes place, and thus this formidable process is 

 brought to an end."] 



ANATOMICAL APPEARANCES. We rarely find the blood liquid in 

 dissection of recent infarctions ; as a rule, it is coagulated. This circum- 

 stance is easy to account for, if we reflect that the locality impedes a 

 discharge of the blood, and that, if the patient survive the attack for any 

 length of time, the liquid part is absorbed, while the coagulable portion 

 is retained. The blood is easily expelled from the bronchi by coughing, 

 by the action of the bronchial muscles, and by that of the ciliated epi- 

 thelium, but forced expiration can only empty the vesicles in part, and 

 they have no muscles nor ciliary epithelium. 



Haemorrhagic infarctions which occur in disease of the heart gener- 

 ally vary in size from that of a hazel-nut to that of a hen's egg. They 

 are of a blackish-red or blackish color, completely inelastic, and void of 

 air, so that they can be felt from without like hard knots. Their cut 

 surface presents an irregular, coarse, granulated aspect, from which a 

 brownish-black mass may be scraped off with the scalpel. In the im- 

 mediate vicinity of this sharply-defined spot the lung is usually full of 

 blood and cedematous from collateral fluxion. Its seat, as already men- 

 tioned, is usually at the middle of the lower lobes, or near the roots of 

 the lungs ; more rarely at the surface. Microscopic examination show? 

 the capillaries to be distended by blood-corpuscles, which are also col 

 lected in the tissue outside of the capillaries. 



Where the infarction is of long standing, it looks paler and yellow- 

 ish, the fibrin having undergone fatty degeneration, and the coloring 

 matter of the blood being partially decomposed. Still later, the fatty 

 fibrin is absorbed, and part of the haematin has turned into pigment, 

 and the only remaining trace of the infarction is a blackish induration 

 in the lung. In the rare instances in which an abscess forms it may be- 

 12 



