ON THE ÜRIGIN OF INDIVIDUÁIS.' 



A THEORY OF SLEEP. 



By Professor A. L. Herrera, M. S. A. 



Sleep is not peculiar to man, for it presents itself iu 

 every organism. ''Protozoa themselves sleep," says Milne 

 Edwards, and sleep must, therefore, have quite a general cau- 

 se. Some substances (narcotics, anaesthetics ) provoke sleep 

 either by dehydration or by producing congestión in the ner- 

 vous centres, etc. On the other hand, sleep does not invade 

 every orgau in the same manner; it presents itself sporadi- 

 cally in such organs as happen to be extremely tired, or in 

 those that aré not well fed. It does not, in short, essentially 

 differ from hibernal sleep. 



Let US seek then for a philosophical explanation compri- 

 sing every particular case and requiring no suppositions ñor 



1. See: Memorias de la Sociedad "Álzate." Vol. XI, p. 137-179; 

 219-243. 



