September, 1951]
AMRITAMOY
MUKERJI
131
distance between the rods being wide enough to allow the rays of the sun to enter
freely into the cage without any obstruction. A preliminary experiment with
half a dozen rabbits from a separate stock was conducted before the actual experi-
ment with a view to ascertain the extent to which the rabbits got photosensitized
in a given time when exposed to the sun. It was found that 2 hours' continuous
exposure to the sun from 10 a.m. to 12 a.m. when the air temperature near the place
of exposure was just above 70°F. was sufficient to increase the body temperature
of the rabbits by 3°F. to 5°F. above their normal recorded in the shade immediately
before the exposure and induced distressing symptoms, such as, rapid respiration,
panting, screaming and running about in the cage. Experience gained from the
finding of this preliminary experiment was valuable for regulating the daily period
of exposure of the sun group.
Duration of exposure. Sun group rabbits were exposed to the sun twice daily,
once between 9-30 a.m. to 11-30 a.m. and again between 2-30 p.m. to 3-30 p.m.
exposure, specially between 9-30 a.m. to 11-30 a.m. was not given continuously.
They were exposed for 50 minutes in the beginning and then were removed to the
shade for about 20 minutes for cooling down, again they were exposed for another
50 minutes and then were finally removed to the room. (This process of disconti-
nuous heating prevented the rabbits from being overheated with consequent
distressing symptoms). During 2-30 p.m. to 3-30 p.m. the exposure was generally
continuous and this did not produce any distressing symptoms). Daily exposure of
the above duration was given to the sun group for 10 successive days after each
injection. The weather at Mukteswar during the first 10 days' exposure remained
on the whole clear, but during the second period of exposure from 17 to 26 June,
the weather conditions were unsatisfactory owing to the onset of the monsoon result-
ing in frequent interference with the daily routine of expsoure.
Effect of exposure. While the average normal body temperature of all
the rabbits belonging to both the groups recorded in the room at 9 a.m. was found
to be about 103°F., continuous exposure to the sun from 9-30 a.m. for 50 minutes
induced progressive rise of body temperature 2 to 3°F. over the normal recorded
before exposure, accelerated respiration and tendency to panting. These symp-
toms rapidly disappeared soon after the return of the rabbits to shade. After
an interval of 20 minutes they were again exposed to the sun continuously for
another 50 minutes during which symptoms very similar to those described above
were noticed. Afternoon exposure between 2-30 p.m. to 3-30 p.m. was generally con-
tinuous and the effect of photosensitization was mild. Rabbits with dark-brown
coat colour were much more quickly photosensitized than the whites and the
admixtures of brown and white. Recording of body temperature of the sun group
before, during and after the exposure was always preceded by recording of
body temperature of the shade group. Hyperthermia and consequent increase
in the rate of respiration of the sun group rabbits due to the effects of exposure to
the sun were sharply contrasted with the normal body temperature and the rate
of respiration of the shade group rabbits during the corresponding period.
Meteorological observations
Dry and wet bulb thermometer readings were recorded in the rabbit house
daily at 9-30 a.m. i.e., just before the sun group was removed outside for exposure.