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LXVI. The Croenian Lecture. Bu William Hvdk 



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WoLLASTON, M.D, Sec 



± AM aware that the remarks, which I have to offer on the 

 present occa?;ion, may be thought to bear too little direct 

 relation to each other for insertion in the same lecture; yet 

 any observation respecting the mode of action of voluntary 

 muscles, and every inquiry into the causes which derange> 

 and into the means of assisting the action of -the heart and 

 blood-vessels, must be aHowed to promote the design of 

 Dr. Croone, who instituted these annual disquisitions. 

 And it has always appeared to be one great advantage at- 

 tending the labours of this societv, that it favours the pro- 

 duction of any original knowledge, however small, in a 

 detached form ; and enables a writer to say all that he 

 knows upon a particular subject, without inducing him to 

 aim at the importance of a long dissertation. 



I shall therefore make no apology for divi-ding the fol- 

 lowing lecture into three distinct parts. 



In the first of which I shall treat of the duration of vo- 

 luntary action. 



In the second, I shall attempt to investigate the origin 

 of sea-sickness, as arising from a simple mechanical cause 

 deranging the circulation of the blood. 



In the third, I shall endeavour to explain the advantage 

 derived from riding, and other modes of gestation, in as- 

 sisting the health under various circumstances, in pre- 

 ference to every species of actual exertion. 



Part I. On tlie Duration of Muscular Action, 



The necessity of occasional intermissions from a series of 

 laborious exertions, is within the experience of every one ; 

 the fatigue of continuing the eifort cf any one voluntary 

 muscle without intermission even for a few minutes is also 



I sufficiently known; but there is a third view of the dura- 

 lion of muscular action which appears to have escaped the 

 notice of physiologists ; for I believe it has not hitherto 

 been observed that each cfibrt, apparently single, consists 

 in reality of a great number of contractions repeated at 

 ^extremely short intervals : so short indeed that the inter- 

 mediate relaxation cannot be visible, unless prolonged be- 

 yond the usual limits by a state of partial or general de- 



'bility. 



• From Philosophical Transactions for 1810, Parti. 



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