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rows of flattened cells closely resembling an endothelium, 

 Interspersed among the epithelium of the bronchi, branched 

 connective-tissue cells were found, communicating by their 

 processes with those of the mucosa, and thus forming a 

 pseudo-stomatous tissue by means of which the lympli- 

 canalicular system may be brought into communication with 

 the surface of the bronchial mucous membrane. That such 

 a communication does exist was proved by Sikorsky, who 

 found that coloured particles introduced into the bronchi 

 penetrated into the lymph-spaces of the mucosa. 



Lastly, the perivascular lymphatics are described as origi- 

 nating in the walls of the alveoli by a lymph-canalicular systeni 

 occupied by branched connective-tissue cells, whose processes 

 often project between the epithelium lining the alveoli, and 

 thus form pseudo-stomata, which permit of communication 

 between the cavity of the alveoli and the lymph-canalicular 

 system. The lymphatic trunks formed by the confluence of 

 the capillaries which arise from the lymph- canaliculi 

 accompany the branches of the pulmonary artery and vein, 

 chiefly as distinct vessels running by their side, but often, 

 especially around the smaller arterial branches, the lymphatic 

 vessels are replaced by lymphatic lacunae which communicate 

 freely with each other. The arterial or venous branch was 

 sometimes seen to pass directly through a lacuna, in which 

 it thus becomes invaginated. 



The pathological portion of the work begins with an 

 account of the changes observed in the pleura pulmonum in 

 inflammation. The endothelium was found to germinate 

 around the stomata, more especially in chronic inflammation; 

 and in the course of chronic pyaemia and artificial tuber- 

 culosis the changes found were, (a) thickening of the matrix 

 of the pleura preceded by infiltration Avith lymphoid cells ; 

 (b) hypertrophy of the muscular coat in guinea-pigs, so that 

 the meshes between the muscular bundles become much 

 narrower, and even a continuous muscular membrane may be 

 found in some parts ; (c) the intermuscular lymphatic spaces 

 and many subpleural lymphatic vessels become filled with 

 lymphoid cells, derived, in all probability, partly from the 

 germinating endothelium around the stomata, and partly from 

 emigration from blood-vessels. These plugged lymphatics 

 share in the formation of the characteristic nodules of arti- 

 ficial tuberculosis, so far as the superficial parts of the lung 

 are concerned. The vessels at first only filled with lymphoid 

 cells are converted into cords of adenoid tissue, by an out- 

 growth of their endothelial walls in the form of fine fibres, 

 forming a reticulum between the cells. The cords leave 



