TRANSACTIONS OF SECTION I. 649 
is not understood, but by some it is believed to be simply an expression of 
the phases of activity and rest through which the body passes in the twenty- 
four hours. 
Muscular exercise, the ingestion of food, the stimulating effect of light, 
and tissue activity of any kind have a tendency to raise the body tempera- 
ture, whereas rest and sleep lower it, and the daily temperature rhythm 
may be the resultant effect of these various influences. If this were so, one 
would expect to find that, by inverting the daily routine of life, the 
temperature curve should also be inverted. 
Mosso * and Benedict * have studied the effect of night work and day rest 
and sleep on the temperature rhythm, and both have come to the conclusion 
that the normal temperature curve cannot be inverted by inverting the daily 
routine, for while rest and sleep during the day lower the temperature, work 
during the night does not raise it appreciably. 
These results would appear to show that the daily oscillation of the 
body temperature is not due directly to the causes already mentioned, but 
that it may have a deeper significance, and may indicate a diurnal 
periodicity in the body, comparable in character to the seasonal and lunar 
changes which are known to occur in certain plants and animals. That 
a certain fixity of the temperature rhythm is present in the body is the 
most obvious interpretation of the failure of Mosso and of Benedict to 
invert it. 
Instead of altering the daily routine artificially in a fixed locality, the 
same may be effected in a natural way by changing the locality, for an 
individual who travels round the world from west to east, or vice versa, 
especially in high latitudes, quickly alters his daily routine. 
It was with the view of finding the effect of such a change of locality 
on the temperature rhythm that the author made some observations on his 
own body temperature during a journey eastward from Ithaca, in the 
western part of the State of New York, to Edinburgh, and westward again 
‘from Edinburgh to Winnipeg. Readings were taken from the mouth, 
axilla, and rectum every three hours from 9 a.m. till midnight, and during 
the night at irregular intervals whenever the observer happened to wake up. 
The temperature curve for Ithaca was obtained by recording observations 
for one week before leaving. The eastward journey was begun on the night 
of June 25 and Edinburgh was reached at 9 p.m. on July 4; during the 
voyage Ithaca time was gradually falling behind the local (ship’s) time, 
and at Edinburgh there was a difference of about five hours. If the Ithaca 
thythm had been fixed in the body, one would expect to find that the 
temperature curve should tend to lag behind, so that the sharp morning 
rise, which was found to occur between 7 and 9, would appear later 
each successive day, and finally fall between 12 and 2 p.m. in Edinburgh. 
Such, however, was not the case. The temperature curve seemed to be 
governed entirely by local time and not by Ithaca time. 
Six weeks were spent in Scotland, the journey westward was begun 
on August 14, Winnipeg being reached on August 27. The difference in 
time amounts to about seven hours, and it was found, as in the voyage 
eastward, that the temperature rhythm adjusted itself at once to the 
change of routine. The temperature curve in Winnipeg differed in no 
respect from the normal curves in Ithaca and in Edinburgh, and showed 
no trace of the persistence of an Ithaca or Edinburgh rhythm. This 
appears to be in agreement entirely with the observations of Gibson * and 
of Osborne,* made under somewhat similar circumstances. 
1 U. Mosso, Arch. Ital. de Biol., 1887, viii., p. 177. 
? Benedict, Amer. Jour. Physiol., 1904, vol. xi., p. 146. 
$ Gibson, Amer. Jour. of the Medical Sciences, June 1905, p, 1048. 
* Osborne, Jour. Physiol. (Proc.), Jan. 25, 1908. 
