Class III. 2. 1. 1 1. OF VOLITION. 339 



ly publifhed fome fuccefsful cafes of the life of mercurial oint- 

 ment. See Colica Saturnina, I. 2. 4. 8. See Clafs III. 2. 1.4. 

 Dr. J. Alderfon has lately much recommended the leaves of 

 rhus toxicodendron (fumach), from i. gr. to iv. of the dried 

 powder to be taken three or four times a day. Eflay on Rhus 

 Toxic. Johnfon, London, 1793. But it is difficult to know 

 what medicine is of fervice, as the movements of the mufcles 

 muft again be learned, as in infancy, by frequent efforts. 



11. Paraplegia. A palfy of the lower half of the body di- 

 vided horizontally. Animals may be conceived to have double 

 bodies, one half in general refembling fo exactly the other, and 

 being fupplied with feparate fets of nerves ; this gives rife to 

 hemiplegia, or palfy of one half of the body divided vertically ; 

 but the paraplegia, or palfy of the lower parts of the fyftem, 

 depends on an injury of the fpinal marrow, or that part of the 

 brain which is contained in the vertebras of the back ; by which 

 all the nerves fituated below the injured part are deprived of 

 their nutriment, or precluded from doing their proper offices 5 

 and the mufcles, to which they are derived, are in confequence 

 difobedient to the power of volition. 



This fometimes occurs from an external injury, as a fall from 

 an eminence ; of which I faw a deplorable inftance, where the 

 bladder and rectum, as well as the lower limbs, were deprived 

 of fo much of their powers of motion, as depended on volition 

 or fenfation ; but I fuppofe not of that part of it, which depends 

 on irritation. In the fame manner as the voluntary mufcles in 

 hemiplegia are fometimes brought into action by irritation, as 

 in ftretching or pandiculation, defcribed in Seel. VII. 1. 3. 



But the moft frequent caufe of paraplegia is from a protuber- 

 ance of one of the fpinal vertebras ; which is owing to the in- 

 nutrition or foftnefs of bones, defcribed in Clafs I. 2. 2. 17. 

 The cure of this deplorable difeafe is frequently effected by the 

 flimulus of an iffue placed on each fide of the prominent fpine, 

 as firfl publifhed by Mr. Pott. The other means recommend- 

 ed in foftnefs of bones fhould alfo be attended to ; both in re- 

 flect to the internal medicines, and to the mechanical methods 

 of fupporting, or extending the fpine •, which laft, however, in 

 this cafe requires particular caution. 



1 2. Sommts. In fleep all voluntary power is fufpended, fee 

 Sect. XVIII. An unufual quantity of fleep is often produc- 

 ed by weaknefs. In this cafe fmall doles of opium, wine, 

 and bark, may be given with advantage. For the periods of 

 fteep, fee Clafs IV. 2. 4. 1. 



The fubfequent ingenious obfervations on the frequency of 



the 



