C 159 3 



XXIL On the colouring Matter of the black Bronchial Glands 

 and of the black Spots of the Lungs. By George Pearson, 

 M. D. F. R. S. 



Read February 95, 1813. 



In the adult human animal the glands designated bronchial 

 are generally of a black or dark blue colour. These organs, 

 which are allowed to be lymphatic glands, as is well known, 

 are situated at the root of the lungs externally, within cellular 

 membrane, near the bifurcated trachea ; as well as internally 

 on or near the large branches of the bronchi. 



At the age of about twenty years the lungs have a mottled, 

 or marbled appearance, from black and dark blue spots, lines, 

 and points disseminated immediately under the transparent 

 pulmonary pleura. As hath been repeatedly observed, the 

 lungs generally become more dark coloured proportionately 

 to their age. Accordingly at upwards of' sixty-five or seventy 

 years of life, they often appear almost uniformly black, from 

 the number and congeries, or coalescence of the maculse, 

 points, and lines just mentioned. Throughout the whole in- 

 terior substance of the lungs the black spots are seen in a 

 great measure corresponding to the external appearance. 



I do not find that any observations and experiments have 

 been madei^to determine the nature or cauise of the black'* 

 colour above described of the pulmonary organs. It is true, 

 a conjecture has been proposed, that sooty matter taken in with 



<t 





