CARBONACEOUS MATTER IN THE LUNGS. 365 



surface of the organs. The deposit is generally most abun- 

 dant at the summit of the lungs. This matter also exists in 

 the lymphatic glands connected with the pulmonary struc- 

 ture, which are sometimes called the u bronchial glands." 

 The nature of this deposit has been the subject of consider- 

 able discussion. Some have supposed that it was connected 

 with melanotic deposits, and consisted of ordinary pigmentary 

 matter ; but chemical investigations have now pretty conclu- 

 sively demonstrated that it is nothing more nor less than 

 carbon. It exists in great abundance in the lungs of miners, 

 who inhale great quantities of carbonaceous particles, and of 

 those who are much exposed to the inhalation of smoke. 

 These facts, taken in connection with its absence in young 

 persons and the inferior animals, and its small quantity, even 

 in old age, in those who inhabit villages and are not exposed 

 to a smoky atmosphere, point to its introduction from with- 

 out. The subject has been most completely and ably inves- 

 tigated by Robin, who has come to the conclusion that the 

 matter is really carbon ; that it is introduced in fine particles 

 in the inspired air, and that, once in the lungs, it penetrates 

 the tissue, not by absorption, but by mechanical action, until it 

 finds its way beneath the pleura and into the intercellular 

 substance. From the fact that carbon is insoluble, its penetra- 

 tion must be mechanical ; and, when found in the lymphatic 

 glands, it is carried there by the absorbent vessels. When 

 it has penetrated the substance of the tissues, it can no more 

 be removed than the tattooing beneath the skin ; indeed, the 

 deposition in the lungs may be compared very aptly to the 

 process of tattooing. 



The mechanism of its introduction is the following : The 

 little sharp, almost microscopic, particles are inhaled and 

 come in contact with the delicate walls of the air-cells, in 

 which they are imbedded under a certain pressure. When 

 any part is subject to pressure, it is well known that it gives 

 way by absorption, the pressure facilitating the removal of 

 worn-out matter, but interfering with the deposition of new 



