(j(j PHYSIOLOGY. 



can exert: for example, I cannot lift the tenth part of the 

 weight which other persons can raise. Abstracting, therefore, 

 from the powers exciting, the actions are performed with more 

 or less strength ; this is called VIGOUR. The distinction be- 

 tween mobility and vigour is of use, because mobility is some- 

 times connected with the most remarkable states of weakness." 

 XC. The mobility and vigour of muscular fibres (LXXXIX.) 

 can both of them be increased or diminished by various means. 

 Whatever can excite the contraction of muscular fibres is called 

 a STIMULUS ; and, in general, the means of exciting contraction 

 are called STIMULANT POWERS. The means of diminishing the 

 mobility and vigour of muscular fibres are called SEDATIVE 

 POWERS. " I thought it thus necessary to define stimulus, in 

 order to take off the notion of its being considered as the action 

 of a sharp-pointed body. We can excite the action of the heart 

 by the prick of a needle, but we can also do it by blowing in 

 air ; and we say that the influx of venous blood is the common 

 stimulus to the action of the heart." 



XCI. The inherent power (LXXXVI.) is supposed to be 

 more vigorous, moveable, and permanent in certain muscular 

 fibres than in others. " It is well known that this inherent 

 power is more permanent in certain animals, as frogs, lizards, 

 tortoises, and the other amphibia, after what we consider as 

 death has taken place ; in these it remains longer than in the 

 fibres of warm-blooded animals. In the same person also, at 

 different times, the muscular fibres are more vigorous and move- 

 able ; and it is obvious that these conditions of vigour, mobility, 

 or duration, may be different in different parts of the same body. 

 I chose the term supposed, however, because the experiments 

 adduced in proof of this difference, are not absolutely decisive. 

 With regard to the permanency, Haller thinks it greatest in the 

 heart ; but the experiments of Huber lead to the conclusion, that 

 the inherent power is not more permanent in the heart than in 

 other parts ; for, if you open the abdomen first, and the thorax 

 afterwards, the power appears longest in the heart ; but, if you 

 open the thorax first, and the abdomen last, it is lost sooner in the 

 heart than in the intestines. The permanency, therefore, is doubt- 

 ful. Some time after death a stimulus applied to the heart will 



