This arrangement prevents vibration
of the plate and blurring of the image. The camera is mounted by two
lateral axles with screw clamps upon two iron stands, such as are in
common use in chemical laboratories. A brass rod attached to the tube
steadies it, and allows it to be screwed fast at any angle
corresponding to the angle at which the heart is placed. It is thus
easy to put a manometer tube in the femoral artery of an animal, bend
it up alongside of the exposed heart, and simultaneously photograph
the cardiac contraction and the degree of rise of the fluid in the
manometer(!). The tube is arranged like the draw tube of a microscope.
It is made long, so as to admit of taking small hearts at life-size.
The stand carries a support for the frog or other animal to be
experimented upon, and a bottle of physiological salt solution kept
warm by a spirit lamp beneath.
[Illustration: FIG. 2.--INTERIOR OF THE CAMERA.]
The whole apparatus is readily packed in a small space. I have already
taken a number of photographs of various hearts and intestines with
it, and the contraction of the heart of the frog produced by
_Strophanthus hispidus_, the new cardiac stimulant, is seen in Fig. 3,
taken by this new instrument. The apparatus has the great advantage
that six photographs of a single cardiac pulsation, or of any muscular
contraction, may be easily taken in less than one second, or, by
simply turning the crank slower, they may be taken at any desired rate
to keep pace with the rhythm of the heart.
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