OF UREA AKD HRINAEY WATEE. 
799 
duction of urea is due to many causes, we may not expect to find precise uniformity in 
its relations to temperature ; and hence we find that, after the temperature had attained 
its maximum, the urea continued to increase for a short period ; but when the propor- 
tionate amount of urea to temperature is tested in the two highest and two lowest months 
respectively, it is found to be almost absolutely the same, viz. 11'5 grs. and 11 '8 grs. to 
each degree. 
The foregoing refers to the production of urea, since it comprehends lengthened 
periods ; and the infiuence of temperature is very clear ; but on considering the influence 
of that agent during short intervals, as in sudden changes of temperature, the acts of 
production and elimination are mixed together and cannot be easily separated. Hence 
the effect of the changes of temperature seems to vary at difierent periods ; and this 
occurs, doubtless, because in some instances the urea is retained longer than in others. 
I have sought to ascertain the effect of sudden changes, and have found great diversity ; 
but commonly the influence was felt on the urinary water on the first, and on the urea 
on the second day. The following are instances of rapid changes of temperature 
associated with the effect upon the urmary secretion (Plate XXXII. fig. 6) : — 
Hujle XXVI. 
I860, Xovember 
15. 
16. 1 17. 
18. 
19. 
20. 
21. 
23. 
23. 
Temperature... 
Urea (same day) 
Urea (next day) 
45-8. 42-6x 48-3. 3^-6. 3^8\ 4i-K 4i'7\ 43-5 3^6x 
grs. \ grs. \ grs. \ grs. \ grs. \ grs. \ grs. \ gi-s. \ grs. \ 
457 >478 ^433 ^485 ^41 3 ^428 >446 >489 ^548 ^403 
478^ 433^ 480-^ 413^ 428 "^ 446^ 489^ 548^ 403/ 
If the temperature and urea on the same day be compared, it will be found that the 
action of temperature is inverse, and in that sense the various parts would correspond 
both in the ascending and the descending series, except at the point at which the 
change in the direction of the lines occurred, as on November 20, when an increase of 
3°‘3 of temperature would be accompanied by an increase of 15 grs. of urea and thus 
break the nde ; but if the effect of the temperature be sought for on the day following 
the variation, the action will be found to be direct and to correspond in every part, as 
is shown in the Table by the low'est line, in which the quantities of urea have been 
placed a day earlier than they actually occurred. 
The following illustration shows a deviation from the rule, in consequence of a very 
large emission of urine on the day of a frost, compensating the greatly diminished quan- 
tity of the preceding day. The urea varied with the temperature of the previous day. 
The urine increased as the temperature fell ; but when the temperature became stationary, 
it offered the compensating alternations before referred to. 
