STUDY OF PULMONARY GLANDERS. 
301 
sensation to the huger of a hard, fibrous nucleus enclosed in 
the elastic tissue of the organ. Upon section, the tubercle 
shows a thick, fibrous envelope intimately embedded in the 
surrounding parenchyma, and a caseous structure of a dirty 
white color, which is easily removed by scraping. But again, 
we very often find in the same lung younger forms, whose 
different aspects correspond to the various periods of devel¬ 
opment. It thus becomes easy to follow the successive 
changes of the superficial tubercles, and also becomes possible 
to judge of the rapidity of the successive transformations, ac¬ 
cording to the number of lesions of a similar type which come 
under our observation. 
The tubercle is first indicated by a rounded ecchymosis 
of a dark red color, with a diameter varying from that of a 
seed of millet to that of a dime. A grayish point soon ap¬ 
pears in the center of the hemorrhagic spot, and spreads 
rapidly. This incipient tubercle has the form of a semi-trans¬ 
parent, homogeneous, gray granulation, and is composed of 
an elastic tissue of a fleshy consistency. Sometimes a trace 
of the primary ecchymosis appears in the form of a rosy are¬ 
ola on the periphery. At a later period, a deep gray focus 
appears of a dirty white color on the center of the gray spot, 
gradually increasing, while the peripheric zone loses its trans¬ 
parency and becomes more dense in its structure; and as 
soon as this density becomes perfect, only a rounded mass of 
a uniform yellowish gray aspect can be recognized, and the 
nodule assumes the characteristics of the adult tubercle 
already described. 
The histological analysis enable us to follow, step by step, 
the successional development of these alterations. The for¬ 
mation of the nodule is preceded by an inflammation of the 
sub-pleural and interlobular lymphatic tracts of the region. 
The pleural and sub-pleural lmyphatic spaces show them¬ 
selves in great part dilated and gorged with round cells; in 
the interlobular connective tissue, the lymphatic vessels are 
also d.stendea ; at some points, dilatations filled with leuco¬ 
cytes, resembling a minuscule closed follicle, are met with. 
The vascular sheaths are infiltrated, and the dilated vessels 
