ORGASM AND IRRITABILITY 229 



organ essentially distinct, and adapted solely for producing it ; and 

 it invariably ends with life or even slightly before death. 



We may be sure that feeling cannot occur in an animal without the 

 existence of a special organ adapted for producing it, — that is without 

 a nervous system. Now this organ is always quite discernible ; for 

 it caimot exist without a centre of communication for the nerves, 

 and hence could not remain unperceived when it is present. This 

 being so, seeing that many animals have no nervous system, it is 

 obvious that sensibility is not a faculty common to all animals. 



Finally, feeling as compared with irritabihty presents in addition 

 this distinctive pecuharity, that it comes to an end with life or even 

 a Uttle before ; whereas irritability is still preserved some time after 

 the death of the individual, and even after it has been divided into 

 fragments. 



The time during which irritability is preserved in the parts of an 

 individual after death varies no doubt with the system of organisation 

 of that individual ; but in all animals it is probably true that irritabihty 

 continues to be manifested after the cessation of life. 



In man the irritabihty of his parts scarcely lasts more than two or 

 three hours after death, or even less, according to the cause of death : 

 but thirty hours after having removed a frog's heart it is still irritable 

 and capable of producing movements. There are insects, in which 

 movements are manifested still longer after they have been deprived 

 of their internal organs. 



From the above account, we see that irritabihty is a faculty peculiar 

 to animals ; that all animals possess it in a high degree in some or all 

 of their parts and that an energetic orgasm is the source of it : we see 

 moreover that this faculty is entirely distinct from that of feehng ; 

 that the one is of very different character from the other, and that since 

 feeling can only result from the functions of a nervous system provided 

 as I have shown with its centre of communication, it only occurs in 

 those animals which possess the required system of organs. 



Let us now consider the importance of cellular tissue in all kinds of 

 organisation. 



