444 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



layers, even Tjlood-stained, especially over an infarctcd lim;;. A noticeable feature of 

 these false membranes, and one that serves to distinguish them from those of ordinary 

 pleurisy, is that they are commonly limited to the surface of the diseased portion of 

 lung, or, if more extensive, that portion which covers sound lung-tissue is much more 

 recent, and has probably been determined by infection from the li(j,uid thrown out 

 into the chest. 



In the lung itself the most varied conditions are seen in different cases and at differ- 

 ent stages of the disease. The diseased lung is solid, firm, and resistant, seems to be 

 greatly enlarged, because it fails to collapse like the healthy portion vrlieu the chest 

 is opened ; is greatly increased in weight, and sinks in water. 'When cut across it shows 

 a j)eculiar linear marking (marbling) due to excessive exudation into the loose and 

 abundant connective tissue which separates the dili'erent lobules of the ox's lung, from 

 each other. This exudation is either clear, and therefore dark, as seen by reiiected 

 light, or it is of a yellowish-white, and when filled with it the interlobular tissue ap- 

 pears as a network, the meshes of which vary from a line to an inch across, and hold 

 in its interspaces the pinkish-gray, brownish-red, or black lung tissue. 



When only recently attacked the lung may present two essentially different appear- 

 ances. 



1. Most frequently the changes are most marked in the interlobular connective tis- 

 sne, which is the seat of an abundant infiltration of clear liquid, a sort of dropsy, 

 while the lung-tissue, surrounded by this, retains its normal pinkish-gray color, and 

 is often even paler, and contains less blood than in health. It has, in short, become 

 compressed by the surrounding exudation, and air and blood have been alike in great 

 part expressed from its substance. (See Plate I.) This extreme change in the tissue 

 surrounding the lobules and the comparatively healthy appearance of the lobules 

 themselves, have led many observers to the conclusion that the disease commenced in 

 the connective tissue beneath the pleura and extended to the proper tissue of the lung. 

 There is, however, as pointed out by Professor Yeo, a coexistent disease of the smaller 

 air-tubes corresponding to the lobules that are circumscribed by this infiltration, and 

 there is every reason to believe that the infiltration in question is the result of ante- 

 cedent clianges in the air-tubes. 



2. Less frequently we find the lobules of the Inng-tissne presenting the first indica- 

 tions of change. The lobules affected are of a deep red, and more or less shining, yet 

 tough and elastic. They do not crepitate on pressure, yet they are not depressed be- 

 neath the level of the adjacent healthy lung-iissue as they would be if collapsed. The 

 interlobular connective tissue, devoid of ail unhealthy exudation, has no more than 

 its natural thickness, and reflects a bluish tint by reason of the subjacent dark sub- 

 stance of the limg. Here the lung-tissue itself is manifestly the seat of the earliest 

 change — congestion — and the interlobular exudation has not yet supervened. Speci- 

 mens of this kind may be rare, but a number have come under the writer's observa- 

 tion, and in lungs, too, that presented at other points of their substance the excessive 

 interlobular exudation. 



Both of these forms show a tendency to confine themselves to particular lobules and 

 groups of lobules of the lung. They correspond, in short, to the distribution of par- 

 ticular air-tubes and blood vessels, as will be explained further on. The fact, how- 

 ever, is noteworthy as characteristic of the disease, that it attacks entire lobules, and 

 the limits of the diseased lung-tissue are usually sharply marked by the line of con- 

 nective tissue between two lobules, so that one lobule will be found consolidated 

 throughout, and the next in a perfectly natural condition. 



The two forms just described differ also in cohesion and power of resistance. The 

 lung saturated with the liquid exudation has its intimate elements torn apart, and is 

 more friable, giving way readily under pressure, while that in which there is red con- 

 gestion but no extensive exudation retains its natural elasticity, toughness, and power 

 of resistance. 



Another condition of the diseased lung-tissue, more advanced than either of those 

 just described, is the granular consolidation or hepatization. In this condition the 

 affected regions of Inng are as much enlarged as in the dropsical condition, but they 

 are firmer and more friable, and on their cut surface present the appearance of little 

 round granules. These granules are not peculiar to the lung-tissue proper, though 

 most marked on this; they characterize the interlobular connective tissue as well. 

 They consist mainly of ]ymj)hatic cell growths, filling up the air-cells, the smaller 

 air-tubes, the lymph spaces, and the meshes of the connective tissue. The color of 

 these portions varies from a bright reddish-brown to a deep red, according to the com- 

 pression to which the lung-tissue has been subjected by the exudation in the early 

 stages. (See Plate I.) 



Another form of lung consolidation is of a very dark red or black, and always im- 

 plies the death of the portion afiected. The dark asjiect of the diseased lobules forms 

 a strong contrast with the yellowish-white interlobular tissue, excepting in cases 

 where that also becomes blood-stained, when the whole presents a uniform dark mass. 



