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IX. On the ultimate distribution of the Air-passages , and the formation of the Air- 
cells of the Lungs. By William Addison, Esq., F.L.S., Member of the Royal 
College of Surgeons, and of the Council of the Worcestershire Natural History 
Society. Communicated by Robert B. Todd, M.D., F.R.S. 
Received March 3, — Read April 7, 1842. 
The opinions of anatomists have been much divided as to the manner in which the 
bronchial tubes terminate ; whether the cells composing a lobule of the lungs have 
free communication with each other, or whether each cell, without any such com- 
munication, receives the inspired air by a single bronchial ramification only. 
The latter opinion, derived from the results of Reisseissen’s investigations, prevails. 
Malpighi was the first to describe the air-vesicles of the lungs, and the air-tubes 
ending in them*. 
Helvetius attempted to prove that these Malpighian vesicles were nothing more 
than common cellular tissue, diffused without order through the lungs, and that the 
air proceeding thither through the minute air-tubes, not only passes easily from cell 
to cell, but likewise from the lobules into their interstices, and finally diffuses itself 
through the whole lung. 
Haller adopted the opinions of Helvetius. “ The vesicles of the lungs,” he says, 
“do not receive the air by a single orifice from the windpipe as into an oval grape 
or phial, but the air exhaling from the least branches freely spreads from any one 
part of the lungs into all the rest, and returns again in like manner ; neither is the 
cellular fabric of the intervals between the lobules shut up from the vesicles of the 
lungs, nor are the lesser lobes surrounded by any peculiar membrane'f'.” 
Reisseissen, in his work De Fabrica Pulmonum, discourses of the labours of his 
predecessors, and refers particularly to the opinions entertained by Helvetius and 
Haller ; and then, aided in his researches by a microscope, and by various methods of 
inflation and injection, he attempts to controvert them, and to prove that the cells in 
each lobular subdivision have no communication with those of the adjoining ones, 
in the manner of cellular tissue. “ The air-cells,” he says, “ are the cuts de sac termi- 
nations of the air-tubes, and are perfectly independent of one another^.” 
* M. Malpighi de Pulra. Epistol. 1 and 2, ad A. Borellum, 1661. Epistola 1. de Pulm. Published at the 
end of the Exercit. de Vise. Struct, p. 220, &c. 
t Haller (Von Albert), Elementa Physiologise : Cap. De Respiratione. 
I “ Inde jam facile colligitur, singulas per pulmonum faciem vesiculas, cellulasve aeriferas, csecos esse ex- 
tremorum canaliculorum fines, easque ingenti numero distributas, massam illam conficere quae spumosa ut est 
plurimis contextus cellulosus videbatur.” — Op. citat., p. 56. 
