Class III. 2. i. 10. OF VOLITION. 337 



for many minutes without attempting to drink, or withdrawing 

 his hand. He never fpoke, and it was at firft neceffary to 

 compel him to drink broth -, he recovered in a few weeks with- 

 out relapfe. 



10. Hemiplegia. Palfy of one fide confifts in the total difo- 

 bedience of the affected mufcles to the power of volition. A9 

 the voluntary motions are not perpetually exerted, there is little 

 fenforial power accumulated during their quiefcence, whence 

 they are lefs liable to recover from torpor, and are thus more 

 frequently left paralytic, or difobedient to the power of volition, 

 though they are fometimes ftill alive to painful feniation, as to 

 the prick of a pin, and to heat ; alfo to irritation, as in ftretch- 

 ing and yawning ; or to electric (hocks. Where the paralyfis 

 is complete the patient feems gradually to learn to ufe his limbs 

 over again by repeated efforts, as in infancy -, and, as time is re- 

 quired for this purpofe, it becomes difficult to know, whether 

 the cure is owing to the effect: of medicines, or to the repeated 

 efforts of the voluntary power. 



The difpute, whether the nerves decuffate or crofs each other 

 before they leave the cavities of the fkull or fpine, feems to be 

 decided in the affirmative by comparative anatomy j as the op- 

 tic nerves of fome fifth have been fhewn evidently to crofs each 

 other •, as feen by Haller, Elem. Phyfiol. t. v. p. 349. Hence 

 the application of blifters or of ether, or of warm fomentations, 

 mould be on the fide of the head oppoiite to that of the affected 

 mufcles. This fubject mould neverthelefs be nicely determin- 

 ed, before any one fhould trepan for the hydrocephalus inter- 

 nus, when the difeafe is (hewn to exift only on one fide of the 

 brain, by a fquinting affecting but one eye ; as propofed in 

 Clafs I. 2. 5. 4. Dr. Sommering has fhewn, that a true decuf- 

 fation of the optic nerves in the human fubject actually exifts, 

 Elem. of Phyfiology by Blumenbach, tranflated by C. Caldwell, 

 -Philadelphia. This further appears probable from the oblique 

 direction and infertion of each optic nerve, into the fide of the 

 eye next to the nofe, in a direct line from the oppofite fide of 

 the brain. 



The vomiting, which generally attends the attack of hemiple- 

 gia, is mentioned in Sect. XX. 8. and is fimilar to that attend- 

 ing vertigo in fea-ficknefs, and at the commencement of fome 

 fevers. Black (tools fon etimes attend the commencement of 

 hemiplegia, which is probably an effufion of blood from the 

 biliary duct, where the liver is previoufly affected ; or feme blood 

 may be derived to the inteftines by its efcaping from the vena, 

 cava into the receptacle of chyle during the diltrefs of the para- 

 lytic attack •, and may be conveyed from thence into the intef- 

 Vol. II. U u tines 



