218 
ON DISEASES OF THE LUNGS IN HORSES. 
tuated to the ribs. It is often accompanied by mucous and sibilous rales. 
When the fluid contained in the cavern comes to flow into the bronchia, and 
thence to be expelled by expectoration, the air, in passing into this cavity, 
ordinarily terminated by a cul-de-sac, should the cavity be near the ribs, gives 
to the ear an inordinately loud sound, called cavernous respiration. When the 
cavernous rale follows upon circumscribed absence of the respiratory mur¬ 
mur, it becomes the sign of distinction between the bronchial and parench^ona- 
tous structures under disease in that situation : this indication, in combina¬ 
tion with such as are furnished by the discharges from the nose, and the air 
expired, may enable us to form some idea of the disease that has occasioned 
the cavern. One observation we would make here, to prove the importance 
of immediate auscultation, and that is, when the expired air is impregnated 
with the odour characteristic of gangrene, and the cavernous rale is distinct 
and circumscribed, we may affirm, during fife, that such a lobe of the lungs is, 
in this part, the seat of an anormal cavity resulting from mortification. This 
rale is also one of the best indications we possess of morbid alterations in the 
lungs of our domestic animals. 
PuEURAL, SouxDS. —When fluid becomes effused into the pleural sacs, we 
directly imagine that it wfil discover itself by a rumbling, or by undulation, 
during inspiratio n and expiration: observation, however, proves that this is 
not always the case—that, in fact, these signs become manifest only in certain 
states, as wifi be seen hereafter. We find an exposition of these S 3 Tnptoms 
in a case of hydrothorax published by M. Massot, which he recovered by tap¬ 
ping. “ When the ear is applied,” says he, “ beneath the sternum, a duU, 
confused, drawling sound is heard, something similar to the noise made by 
rolling a cask containing liquid.” This observation is confirmed by M. Dan- 
di’ieu in a case of carditis, with water in the pericardium, in a cow, narrated 
by him in the “ Recueti. de Mddecine Veterinaire^' vol. iii, p. 488. “ I ap¬ 
plied,” observes M. Dandrieu, “ my ear against the left side of the thorax, and 
I heard a slight confused noise, which I presumed to be caused by a fluid 
already partly effused into the cavity of the pleura, and, perhaps, even into 
the pericardium.” M. Leblanc seems to confirm both these accounts, when 
he says, in speaking of pleural sounds, that “ at one time, kinds of grumbling 
(as of the bowels) are heard; at another, spumous sounds, if I may so ex¬ 
press myself; at a third time, a rumbling sound; the first and last are ordi¬ 
narily heard towards the lower part of the chest, supposing effusion to have 
taken place.” 
Experience has convinced me that the presence of fluid cannot with cer¬ 
tainty be made out by these signs, except under two circumstances :—1st, when 
false membranes have been recently formed; 2dly, whenever gas becomes 
mingled with the fluid : whether it be generated by the fluid itself, be exhaled 
by the pleura, or get accidental admission into the cavity, the result is, that 
agitation produces froth, and then the spumous rMe, combined with rumbling, 
becomes audible at the bottom of the thorax, and the less the quantity of fluid, 
the louder the noise. Should there exist both fluid and false membranes, the 
sound becomes modified, approaching to rumbling, or rather to the guggling 
sound of a bottle emptying itself while its neck is full, but much more feeble. 
This noise has always appeared to us to ensue whenever, with the effusion, 
there were present false membranes which had so formed or arranged them¬ 
selves as to have small areolae., or cavities of various capacities, into which the 
fluid entered during the act of respiration. In every case of hydrothorax 
without false membranes, and the presence of gas in the cavity, that has come 
under our observation, even when the like was produced by the injection of 
warm water into the chest, with the precaution to suffer the admission of as 
little air as possible, we have on no occasion heard any sound produced hy 
