50 THE CAUSATION OF DISEASE. 



altering E causes rhythmical alterations of functions. This is 

 what determines the rhythm of sleep and the peculiar rhythm 

 of temperature, noticeable in man, at all events. In those 

 parts of the world where the rhythm of day and night is 

 absent altogether, the inhabitants are wont to take their sleep 

 in snatches, and we may be quite sure that there is considerable 

 difference between them and ourselves in respect of many of 

 the bodily rhythms. It would be very interesting to make 

 physiological observations as regards temperature, &c, among 

 the inhabitants of such countries, for the rhythm of day and 

 night also determines many others in our bodies — e.g., the hours 

 of our meals, and therefore of the important processes of diges- 

 tion and absorption — processes whose influences are felt through 

 the entire body ; it also determines, or should do, a rhythmical 

 emptying of the rectum, and perhaps even of the bladder. 



Now, it is interesting to note that the subjection of our body 

 to this rhythmically altering E leads to rhythmically recur- 

 ring changes, even after we cease to continue the rhythmical 

 practices. In other words, we can educate the body to go 

 through rhythmical changes. These we may term rhythmical 

 habits. Thus man can educate himself to feel sleepy at a 

 definite hour at night ; to wake at a particular time in the 

 morning, and that too — note well — no matter what hour he 

 goes to bed, thus showing that the awakening is not necessarily 

 due to mere satiation in the matter of sleep. He can further 

 educate himself to wake at a certain hour in the night, in 

 order to pass water or what not, and, in this regard, it is 

 worthy of note — I have observed this many times — that if 

 an individual perchance wake up one night to pass water, 

 there is a great likelihood that he will do so two or three nights 

 in succession. A man can further educate himself (and for 

 the matter of that, many of the lower animals can also be 

 taught) to defecate at a certain hour, always after breakfast, 

 for instance, and so exacting is this rhythm, that very often 

 if the individual do not go to stool at the proper time, if 

 he delay an hour, or perhaps even half-hour, he will fail to 

 have a motion. We can further educate ourselves to feel 

 hungry at particular hours. " Yes," it may be retorted, 

 " because the last meal is digested, and the tissues are 



