8 BIOLOGICAL AND MICROSCOPICAL DEPARTMENT. 



Section to some characteristics of the elastic fibres, to wit, first, 

 the Delta (a) rather than simple Y shape frequent among the 

 fragments, which he attributed to the greater resistance at the 

 meeting-point of the walls of three air-vesicles to any disinte- 

 grating process ; and second, the transverse fracture of its com- 

 ponent elastic filaments, resembling that of an India-rubber thread, 

 instead of displaying a frayed-out appearance similar to that pre- 

 sented at the extremity of a broken cotton or linen string. 



By these peculiarities pulmonary elastic tissue can generally be 

 distinguished from folds in the walls of boiled-stai'ch corpuscles ; 

 from mycelial threads of fungi (which, when dichotomous, often 

 have stem and branches of nearly the same size) ; and from vege- 

 table fibres, which seldom break transversely, and which, when 

 split, generally assume the Y and not the Delta shape. ( Vide 

 paper on the Detection of Lung Tissue in Sputum, in the Neto 

 York State Medical Society'' s Transactions for 1871.) 



