140 Dr. E. Klein on the Anatomy of [Jan. 29, 



solution of Berlin blue, the cavity of many of the capillaries in the neigh- 

 bourhood of those interalveolar trabeculae stops short, but the injecting 

 material can be traced into the nucleated filaments which enter those tra- 

 beculaB. Prom the study of a great number of specimens, taken from 

 lungs in different stages of the process of artificial tuberculosis, I have 

 reason to believe that the first parts which undergo inflammatory changes 

 are the ultimate branches of the pulmonary artery and the capillaries next 

 to them, and that the morbid process extends from them to the corre- 

 sponding lymphatics. 



I have already mentioned that, where the alveolar septa become 

 thickened, the epithelium of the alveoli becomes gradually changed, so as 

 completely to fill the cavities of the alveoli. By this means nodular 

 or patch-like structures are formed, which may be called secondary patches. 

 It may be said, in general, that the epithelial cells proliferate : they en- 

 large; their nuclei divide ; and then the cells themselves divide. In many 

 alveoli there appear, besides isolated epithelial cells, with or without car- 

 bon particles in their substance, numerous small lymphoid corpuscles. 

 In some of the alveoli the enlarged epithelial cells become fused together 

 to one large mass of granular protoplasm, which contains a number of 

 nuclei in its periphery ; this represents, in the true sense of the term, a 

 " giant cell." We may therefore say that, at an early period, these patches 

 consist of trabeeulae, which represent the thickened interalveolar septa and 

 their meshes (the alveoli), and that the latter are filled either with small 

 cells or with giant cells, or rather with multinuclear protoplasmic cylin- 

 drical masses. These secondary patches gradually increase in size, by 

 the extension of the adenoid metamorphosis of the alveolar septa and the 

 changes of the capillary blood-vessels, indicated above. 



A perivascular cord may become furnished with a number of lateral 

 nodules of adenoid tissue from the assumption, by adenoid interalveolar 

 cords, of the contents of alveolar cavities into their own tissue. Where, 

 however, the alveolar cavities contain giant cells, other remarkable changes 

 take place. These are as follows : The cylinders of multinuclear proto- 

 plasm grow and divide into a number of giant cells, which gradually be- 

 come converted into a tissue to a certain extent resembling adenoid tissue, 

 but differing from it in many respects. Thus the giant cells give origin 

 to a more or less regular network of nucleated cells, which, consisting at 

 first of granular substance, soon assume the appearance of a more or less 

 distinct fibrillar substance ; in their meshes lie only a limited number 

 of lymphoid cells. This tissue spreads very rapidly, and finally undergoes, 

 from the centre outwards, a fibrous degeneration, which becomes the seat 

 of cheesy deposits. 



Different lungs are somewhat different in this latter respect. In some 

 cases the transformation of the giant cells into a network of nucleated 

 cells goes on very rapidly ; and then the cheesy metamorphosis is also soon 

 established. In other cases the growth of the network of nucleated cells 



