Prior to an experiment, the subject is usually given either a stipulated
diet for a period of time varying with the nature of the experiment or,
as in the case of some experiments, he is required to go without food
for at least 12 hours preceding. Occasionally it has been deemed
advisable to administer a cup of black coffee without sugar or cream,
and by this means we have succeeded in studying the early stages of
starvation without making it too uncomfortable for the subject. The
stimulating effect of the small amount of black coffee on metabolism is
hardly noticeable and for most experiments it does not introduce any
error.
The urine is collected usually for 24 hours before, in either 6 or 12
hour periods. During the experiment proper urine is voided if possible
at the end of each period. This offers an opportunity for studying the
periodic elimination of nitrogen and helps frequently to throw light
upon any peculiarities of metabolism.
Even with the use of a long-continued preceding diet of constant
composition, it is impossible to rely upon any regular time for
defecation or for any definite separation of feces. For many experiments
it is impracticable and highly undesirable to have the subject attempt
to defecate inside the chamber, and for experiments of short duration
the desire to defecate is avoided by emptying the lower bowel with a
warm-water enema just before the subject enters the chamber. Emphasis
should be laid upon the fact that a moderate amount of water only should
be used and only the lower bowel emptied, so as not to increase the
desire for defecation.
The clothing is usually that of a normal subject, although occasionally
experiments have been made to study the influence of various amounts of
clothing upon the person. There should be opportunity for a comfortable
adjustment of the stethoscope and pneumograph, etc., and the clothing
should be warm enough to enable the subject to remain comfortable and
quiet during his sojourn inside the chamber.
The rectal thermometer, which has previously been carefully calibrated,
is removed from a vessel of lukewarm water, smeared with vaseline, and
inserted while warm in the rectum to the depth of 10 to 12 centimeters.
The lead wires are brought out through the clothing in a convenient
position.
The stethoscope is attached as nearly as possible over the apex beat of
the heart by means of a light harness of canvas. In the use of the
Bowles stethoscope, it has been found that the heart-beats can easily be
counted if there is but one layer of clothing between the stethoscope
and the skin. Usually it is placed directly upon the undershirt of the
subject.
The pneumograph is placed about the body midway between the nipple and
the umbilicus and sufficient traction is put upon the chain or strap
which holds it in place to secure a good and clear movement of the
tambour for each respiration.
The subject is then ready to enter the chamber and, after climbing the
stepladder, he descends into the opening of the chair calorimeter, sits
in the chair, and is then ready to take care of the material to be
handed in to him and adjust himself and his apparatus for the
experiment. Usually several bottles of drinking-water are deposited in
the calorimeter in a convenient position, as well as some urine bottles,
reading matter, clinical thermometer, note-book, etc. Before the cover
is finally put in place, the pneumograph is tested, stethoscope
connections are tested to see if the pulse can be heard, the rectal
thermometer connections are tested, and the telephone, call-bell, and
electric light are all put in good working order. When the subject has
been weighed in the chair, the balance is tested to see that it swings
freely and has the maximum sensibility. All the adjustments are so made
that only the minimum exertion will be necessary on the part of the
subject after the experiment has once began.