THE LUNGS. ]69 



correspond to the smallest lobules of racemose glands, and conse- 

 quently there is no occasion whatever to designate them under 

 any other name, as was done by Rossignol, who calls them 

 infundibula, although it must be allowed that their structure, 

 in many respects, is peculiar. For, whilst in other glands the 

 vesicles, if not quite so isolated from each other as has hitherto 

 been supposed, still enjoy a certain degree of independence, the 

 pulmonary elements corresponding to them, — the air-cells, — 

 are, to a considerable extent, confluent with each other, so that 

 all the vesicles belonging to one lobule open, not into ramifica- 

 tions of the finest bronchial twig going to it, but into a common 

 space, from which the air-vessel is afterwards developed. That 

 this is the true condition of these parts is most readily shown 

 when sections, in various directions, of an inflated and dried 

 lung are prepared, or a preparation injected with a coloured 

 resinous material is corroded by hydrochloric acid. In pre- 

 parations of this kind, vesicles either terminal or otherwise pe- 

 dunculated, or opening independently, are never met with ; on 

 the contrary, they always open in such a way, one into the other, 

 and coalesce to such an extent, as, in the aggregate, to form, 

 most usually, a pyriform sacculus, with sinuous walls. These 

 sacculi, which are also identical with the finest lobules, or the 

 infundibula of Rossignol, must not> however, be regarded as 

 sacs, furnished on their walls with closely placed simple cells or 

 alveoli, the latter, on the contrary, being always grouped in such 

 a way that many of them do not open directly in the larger space, 

 but first into other alveoli, and through them into the common 

 cavity. An idea of the whole relations of these parts may be 

 best arrived at if each pulmonary lobule be viewed as an 

 amphibian lung in miniature, or if it be conceived that the 

 outer surface of the dilated extremities of the bronchial tubes 

 is thickly beset with numerous racemose groups of vesicles, the 

 constituents of which all open into one another and into the 

 common cavity. Understood in this way, the structure of the 

 lungs, then, does not differ in the least, in any important respect, 

 from that of the other racemose glands, except that in the former, 

 at all events in the adult, a partial confluence of the gland- 

 vesicles or air-cells of a lobule, appears to have taken place, the 

 dissepiments between them being here and there broken 

 through and reduced to isolated trabecule, as Adriani correctly 



