SPASM OF THE DIAPHRAGM. 263 



morbid apiipavairce than tliat of mere compression. Tlie disease of a 

 mucous membrane spreads to other parts— that of a serous one is generally- 

 isolated. It was to limit the progress of disease that this difference of 

 structure between the organ and its membrane was contrived. 



The investing membrane of the lungs and that of the heart are in con- 

 tinual contact with each other, but they are as distinct and unconnected, 

 as if they were placed in different parts of the frame. Is there no meaning 

 in this ? 



It is to preserve the perfect independence of organs equally important, 

 yet altogether different in structure and function— to oppose an insuperable 

 barrier to hurtful sympathy between them, and especially to cut off the 

 communication of disease. 



Perhaps a little light begins to be throAvn on a circumstance of which 

 we have occasional painful experience. While we may administer physic, 

 or mild aperients at least, in pleurisy, not only ^ith little danger, but with 

 manifest advantage, we may just as well give a dose of poison as aphysic- 

 baU to a horse labouring under pneumonia. The pleura is connected with 

 the lungs, and with the kmgs alone, and the organisation is so different, 

 that there is very little sympathy between them. A physic-ball may, 

 therefore, act as a counter-irritant, or as giving a new determination to the 

 vital current, without the propagation of sympathetic irritation ; but the • 

 lungs or the bronchial tubes that ramify through them are continuous with 

 the°mucous membranes of the digestive as well as all the respiratory 

 passages ; and on accomit of the continuity and similarity of organisation, 

 there °is much sympathy betAveen them. If there is irritation excited at 

 the same time in two different portions of the same membrane, it is pro- 

 bable that, instead of being shared between them, the one will be trans- 

 ferred to the other — will increase or double the other, and act with fear- 

 ful and fatal violence. 



SPASM OF THE DIAPHRAGM. 



The diaplu-agm is subject to injury and disease of a serious and varied 

 character. Whatever may be the orig-inal seat of thoracic or abdominal 

 ailment, the diaphragm soon becomes irritable and inflamed. This accounts 

 for the breathing of the horse being so much affected under every inflam- 

 mation or excitement of the chest or belly. The irritability of this muscle 

 is often evinced by a singular spasmodic action of a portion, or the whole 

 of it. 



Mr. Castley, in 'The Veterinarian' for 1831, thus describes a case of 

 it :— ' A horse had been very much distressed in a run of nearly thirteen 

 miles, without a check, and his rider stopped on the road towards home, 

 to rest him a little. With difficulty he was brought to the stable. Mr. 

 Castley Avas sent for, and he says,—" Wben I first saw the animal, his 

 breathing and attitude indicated the greatest distress. The prominent 

 svmptom, however, was a convu.lsive motion, or jerking of the whole body, 

 audible at several yards' distance, and evidently proceeding from his 

 inside ; the beats appeared to be about forty in a minute. On placmg my 

 hand over the heart, the action of that organ could be felt, but very in- 

 distinctly ; the beating evidently came from behind the heart, and was 

 most plainly to be felt in the direction of the diaphragm. Again placing 

 my hand on the abdominal muscles, the jerks appeared to come from 

 before backwards ; the impression on my mind, therefore, was, that this 

 was a spasmodic aflTection of the diaphragm, brought on by violent dis- 

 tress in ruiraing." ' 



]\lr. Castley's account is inserted thus at length, because it was tho 

 fii'st of the kind on record, with the exception of an opinion of Mr. 



