ORGASM AND IRRITABILITY 227 



in these parts. I have observed and watched these movements and 

 am convinced that they have nothing in common with animal 

 irritability. See what I have already said, pp. 51-53. 



Although nature has doubtless only one general plan for the pro- 

 duction of living things, she has everywhere varied her means, when 

 diversifying her productions, according to the circumstances and 

 objects on which she worked. But man is always striving to confine 

 her to the same methods ; for the idea that he has formed of nature is 

 still indeed far from that which he ought to entertain. 



How great are the efforts that have been made to discover sexual 

 reproduction every^vhere throughout the two kingdoms of hving bodies ; 

 and in the case of animals to attribute to all of them nerves, muscles, 

 feehng and even will, which is necessarily an act of intelUgence ! 

 How profoundly different nature would be, if she was really limited 

 in the ways that we imagine ! 



We have just seen that orgasm has very different degrees of intensity, 

 and consequently has effects that vary according to the nature of 

 the living bodies in which it occurs, and that in animals alone does it 

 give rise to irritabiUty. We now have to enquire into the nature of 

 this remarkable phenomenon. 



Irkitability. 



IrritabiUty is the faculty possessed by the irritable parts of animals, 

 of producing sudden local manifestations which may occur at any 

 point on the surface, and may be repeated as often as the exciting 

 cause acts upon the susceptible regions. 



The manifestations consist in a sudden contraction and shrinkage of 

 the irritated point, a shrinkage characterised by the closing in of 

 neighbouring points upon that which is affected, but soon followed 

 by a contrary movement, that is to say by a distension of the irritated 

 point and neighbouring parts ; so that the natural condition of the 

 parts distended by orgasm is promptly re-established. 



I said at the beginning of this chapter that orgasm is formed and 

 maintained by caloric, that is a penetrating expansive invisible fluid 

 which passes slowly through the soft parts of ammals and produces 

 in them a tension or kind of erethism. Now if some impression is made 

 upon any such part so as to instigate a sudden dissipation of the in- 

 visible fluid distending it, the part immediately shrinks and contracts : 

 but if a new supply of expansive fluid is instantly developed and 

 distends it afresh, it then reacts immediately and so produces the 

 phenomenon of irritabiUty. 



Lastly, since the parts in the neighbourhood of the point affected 

 themselves suffer a sUght dissipation of the expansive fluid distend- 



