OBSERVATIONS ON PILARIS. 65 



First — The rapidity of the current is diminished in the recum- 

 bent posture, and {in women and children at least) still further 

 during sleep. It seems probable that there may also be an integral 

 change in the relation of the red and white corpuscles approaching 

 that which takes place when the circulation is retarded in the web 

 of a frog's foot. This modiJBcation of the internal constitution of 

 the main current may cause the FilaricB to adhere to the sides of 

 the vessels during rapid circulation, and to fall into the stream 

 when it moves more slowly. 



Second — The oxygenation of the blood at night and in repose 

 is supposed to be less complete than during the day ; although 

 some experiments made by Pettenkofer and Voit point to an oppo- 

 site conclusion, and make it appear that of the total amount of 

 oxygen taken in during twenty-four hours 67 per cent, is taken in 

 by night, and only 33 per cent, by day ; 58 per cent, of the 

 carbonic acid eliminated during twenty-four hours being given off 

 in the day, and 42 per cent, by night. From these results Somner 

 drew the inference that sleep was caused by exhaustion of the 

 reserves of oxygen during the waking state, that oxygen was 

 stored during sleep, and that when the equilibrium was re-established 

 by accumulation the subject awoke. This hypothesis is barely 

 tenable, but it is worth while to mention it in this connection 

 because it accords Aviththe presumption that the blood is more — or 

 less — abundantly charged with oxygen during sleep; and this may 

 help to determine the location of the Filarice. 



Third — The temperature of the blood is probably lower, relatively 

 to that of the tissues (or it may be higher) during sleep than in 

 the alternative state, consequent on the presence, or absence, of 

 special elements derived from the food. 



It does not seem likely that there can be any considerable change 

 of condition consequent upon the periodic or occasional discharge of 

 lymph and chyle into the blood ; but it may happen that when the 

 circulation is slow and the body lies recumbent, the parasites are 

 thrown into the main current and therefore appear in greater 

 numbers. It is premature to speculate on the causes of a pheno- 

 menon which may yet prove to be exceptional, but if the conclusion 

 arrived at should be maintained, it will certainly be the duty of 

 physiologists to pursue further into detail, than they have ever yet 

 been carried, certain neglected inquiries as to the altered conditions 

 of the blood during sleep, and when the brain and body are awake. 



