160 ^Memoirs of Erasmus Darwin, M.tfc 



frequent, almost hourly, shocks of electricity from very 

 j small charges might be passed through the head in all direc- 

 tions with probability of good event ; and the use of the 

 trephine, where the affected side can be distinguished. When 

 one eye is affected, does the disease exist in the ventricle 

 of that side ? 



Hydrops thoracis. — The dropsy of the chest commences 

 with loss of flesh, cold extremities, pale countenance, high- 

 coloured urine in small quantity, and general debility, like 

 many other dropsies. The patient next complains of numb- 

 ness in the arms, especially when elevated, with pain and 

 difficulty of swallowing, and an absolute impossibility of 

 lying down for a few minutes, or with sudden starting from 

 sleep, with great difficulty of breathing and palpitation of 

 his heart. 



The numbness of the arms is probably owing mora fre- 

 quently to the increased action of the pectoral muscles in 

 respiration, whence they are less at liberty to perform other 

 offices, than to the connexion of nerves. The difficulty of 

 swallowing is owing to the compression of the oesophagus 

 by the lymph in the chest ; and the impossibility of breath- 

 ing in a horizontal posture originates from this, that if any 

 parts of the lungs must be rendered useless, the inability of 

 the extremities of them must be less inconvenient to respi- 

 ration'; since, if the upper parts or larger trunks of the 

 air-vessels should be rendered useless by the compression 

 of the accumulated lymph, the air could not gain admit- 

 tance to the other parts, and the animal must immediately 

 perish. 



If the pericardium is the principal seat of the disease, the 

 pulse is quick and irregular. If only the cavity of the tho- 

 rax is hydropic, the pulse is not quick nor irregular. 



If one side is more affected than the other, the patient 

 leans most that way, and has more numbness in that arm. 



The hydrops thoracis is distinguished from the anasarca 

 pulmonum, as the patient in the former cannot lie dowm 

 half a minute ; in the latter the difficulty of breathing, which' 

 occasions him to rise up, comes on more gradually ; as the 

 transition of the lymph in the cellular membranes from one 



part 



