198 RESPIRATION. 



inches. The immense size to which the lungs may be inflated, 

 when the chest has been opened, has no relation to our present 

 subject. 



" The cells are invested and connected by the common but deli- 

 cate cellular membrane the general vinculum of the body and 

 must be carefully distinguished from it. In healthy and very re- 

 cent lungs, I have found the cells so unconnected that they were 

 distended in one insulated spot by air cautiously inflated into a 

 fine branch of the bronchiae, while neither the neighbouring cells 

 nor the cellular membrane, which lies between the cells, admitted 

 the smallest portion. If air is forcibly thrown in, the air-cells 

 are ruptured and confounded with the cellular membrane, and 

 both parts distended. 



" The cellular membrane surrounding the air-cells of the lungs 

 is supplied with innumerable blood-vessels divisions of the pul- 

 monary artery and four pulmonary veins, the branches of which 

 accompany the ramifications of the bronchiae h , and, after repeated 

 division, form at length an immense collection of most delicate and 

 reticulated anastomoses. This extraordinary network, penetrating 

 the mucous web on every side, closely surrounds the air-cells, so 

 that the prodigious quantity of blood existing in the pulmonary 

 vessels is separated from the contact of the air by very fine mem- 

 branes only, which Hales estimated as scarcely -^Vs of an inch in 

 thickness. 



" As each ramification of the bronchiae possesses its own 

 bunch or lobule of air-cells, so again each of these possesses a 

 peculiar system of blood-vessels, the twigs of which anastomose 

 in the wonderful network with one another, but scarcely at all 

 with the blood-vessels of the other lobules, as is proved by micro- 

 scopic observations on living frogs and serpents, by minute in- 

 jections, and by the phenomena of vomicae and other local 

 diseases of the lungs." 



The best treatise with which I am acquainted upon the lungs, 

 is the prize commentary of Reisseisen, published by the Royal 

 Academy of Sciences at Berlin in 1808, and printed in 1822, 

 with six beautiful coloured engravings, and a Latin version, under 

 the care of Professor Rudolphi. 1 



h " Eustachius, tab. xxvii. fig. 13." 



1 Francis Daniel Reisseisen, M. D. of Strasburgh, iiber den ban der Lungen, 

 eine von der JC('miglichen Academic der Wissenshaften zu Berlin gekronte Preiss 

 chrift. Berlin, 1822. 



