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Experiments on the contraction of the orbicularis palpebrarum,

levator labii superioris proprius, zygomatici, and risorius, all acting simultaneously. The point on which the thermopile was placed, was situated between 90 and 110 mm. above the centre of the external auditory meatus, and 30 mm. posteriorly to the latter. In the first three experiments, , the pile was on the RIGHT side of the head, and the muscles of the LEFT side were contracted. This arrangement was necessitated by the inability of the subject to contract the muscles of the right side. In the subsequent six experiments, the pile was on the left side as usual, the subject being changed.

1st Experiment.
1° deflection of galvanometer is equal to 0.004237°C.

Rise or fall of temperature.
Time from
commencement Deflections of Thermometric
of contractions. galvanometer. values.

Comments.

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In this experiment the temperature, at the end of the first minute, stood 0·0296° C. above the starting point. By the end of the third minute, this rise had been reduced to 0.0169° C.; but subsequently a fresh rise occurred, the temperature mounting to 0.0423° C. above the starting point, in the fourth minute; but, setting out from this time a

steady fall commenced, 0338° C. below the starting point being noted at the end of the eighth minute. During the last minute of the contractions the temperature fell to 0.055° C. below the starting point. The subsequent period of inactivity was marked by a still greater fall, the maximum depression-at the end of twelve and a half minutes from the commencement of the experiment-being 0:1821° C.; the last fall was, however, probably due to causes other than the muscular action, as in similar cases given before (1st Experiment on extensors of leg, p. 6).

2nd Experiment.
1° deflection of galvanometer is equal to 0.004237°C.

Rise or fall of temperature.
Time from
commencement Deflections of Thermometric
of contractions. galvanometer. values.

Comments.

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Here we have a steady fall of temperature from the beginning to the end of the experiment, probably owing chiefly to a fall of thermal level, and not to the muscular movements.

3rd Experiments. 1° deflection of galvanometer is equal to 0.004237°C. At the end of 0 minutes..... 0°.

Commenced contractions ļ

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In the above experiment, the temperature rose during the first few minutes, reaching at the end of the fourth minute 0.0169° C. above the starting point. After this time, however, it commenced to fall, touching zero at the end of the sixth minute, and passing 0:00423° C. below this point in the half minute following. A recovery to 0.0084° C. above the zero took place in the seventh minute, but the temperature again fell, and when the contractions were stoppedat the end of eight and a half minutes—the reading was 0.0254° C. below the starting point. Three minutes after the close of the contractions, the fall had increased to 0.0338° C., and at the close of the observations-fourteen and a half minutes from the commencement of the experiment-the temperature was still below the zero by 0.0254° C.

4th Experiment. 1° deflection of galvanometer is equal to 0.004237°C. At the end of 0 minutes...... 0° ..........

Commenced contractions, 1, 2, 3, 4, 5, 6, 7, 8, 9

minutes

0°

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During the first nine minutes of contractions, in the above experiment, the temperature was unaffected, but at the end of the tenth minute—when the contractions were stoppeda fall of 0.0211° C. below the starting point had taken place. The temperature remained at this same degree of depression during six minutes of inactivity following the contractions.

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5th Experiment. 1° deflection of galvanometer is equal to 0.004237°C. At the end of0 minutes....

0°............ 0° Commenced contractions. i 1

+ 0.0169°C. 2

+0.00423°C. 3

-0.00423°C. 4

0° 5

-0.0084°C. 6

+0.00423°C. 7

-5°.
....-0.0211°C.

Stopped contractions. 8, 9, 10, 11 minutes... 15 minutes...............

+0.0169°C. ..-0.00423°C.

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In this experiment, at the end of one minute, the temperature rose 0·0169° C. above the starting point; it declined, however, in the succeeding minutes, touching zero at the end of the fourth minute, and passing 0.0084° C. below this point in the fifth minute. The sixth minute showed a temporary recovery to 0.00423° C. above the starting point ; but during the last (seventh) minute of the contractions the temperature fell to 0.0211° C. below the zero. During the subsequent ten minutes of repose, the temperature, at one time, rose to 0.0169° C. above the starting point, but at the close of the experiment it was

0.00423° C. below that point.

6th Experiment.
1° deflection of galvanometer is equal to 0.004237°C.

Rise or fall of temperature.
Time from
commencement Deflections of Thermometric
of contractions. galvanometer. values.

Comments.

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We have here, first, a rise of temperature of 0.0127° C. at the end of the second minute; then a fall, during three minutes, to 0.0127° C. below the starting point ; afterwards a recovery to 0.0084° C. above the zero; and finally a second fall, amounting to 0.0084° C. at the end of nine and a half minutes, and to 0·00423° C. at the close of the contractions. During the first four minutes of repose the temperature fluctuated between 0.0211° C. below and 0.00423° C. above the starting point. At the close of the experiment at the end of the fifteenth minute—the temperature was still below the zero by 0·0127° C.

7th, 8th, and 9th Experiments--each consisting of seven minutes of contractions with five minutes subsequeut repose showed neither rise nor fall of temperature.

The nine experiments on the muscles under consideration may

be classed as follows:

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