SPASMODIC AFFECTIONS. 401 



by the will, or by certain other causes specially appointed by 

 nature for exciting those contractions ; and these other causes I 

 name the natural causes. In a state of health, the moving 

 fibres are contracted by the power of the will, and by the na- 

 tural causes only. At the same time, the contractions pro- 

 duced are, in force and velocity, regulated by the will, or by the 

 circumstances of the natural causes ; and the contractions, 

 whether produced by the one or the other, are always soon suc- 

 ceeded by a state of relaxation, and are not repeated, but when 

 the power of the will or of the natural causes is again applied. 



MCCLVI. Such are the conditions of the action of the mov- 

 ing fibres in a state of health ; but in a morbid state, the con- 

 tractions of the muscles and moving fibres ordinarily depending 

 upon the will, are excited without the concurrence of the will, 

 or contrary to what the will intends ; and in the other functions, 

 they are excited by the action of unusual and unnatural causes. 

 In both cases, the contractions produced may be in two differ- 

 ent states. The one is, when the contractions are to a more 

 violent degree than is usual in health, and are neither succeeded 

 by a spontaneous relaxation, nor even readily yield to an exten- 

 sion, either from the action of antagonist muscles, or from other 

 extending powers applied. This state of contraction is what 

 has been called a Tonic Spasm, and is what I shall name 

 simply and strictly a Spasm. The other morbid state of con- 

 traction is, when they are succeeded by a relaxation, but are 

 immediately again repeated without the concurrence of the will, 

 or of the repetition of natural causes, and are at the same time 

 commonly, with respect to velocity and force, more violent than 

 in a healthy state. This state of morbid contraction is what 

 has been named a Clonic Spasm, and what I shall name simply 

 and strictly a Convulsion. 



In this section, I shall follow nearly the usual division of the 

 spasmodic diseases, into those consisting in Spasm, and those 

 consisting in Convulsion ; but it may not, perhaps, be in my 

 power to follow such division exactly. 



VOL. II. 



