Method of Investigation. 9 



the blood pressure by means of the sphygmomanometer. Since the obliteration 

 of the radial pulse is necessary for the successful determination of the blood 

 pressure, poor success attended its use. In order to enable the attending 

 physician to note the character of the pulse, a provision was made for attach- 

 ing a thin rubber diaphragm to the wrist of the physician and then inclosing 

 this in the outer end of the food aperture in such a manner that no air could 

 enter or escape. On opening the inner end of the food aperture, the subject 

 could then place his hand in such a manner that the physician could obtain 

 the radial pulse. This procedure, unfortunately, could not be used simulta- 

 neously with the sphygmomanometer. It is further to be regretted that the 

 technique of this operation was not completely developed before it was first 

 used, and hence certain slight errors due to leakage of air were unavoidable on 

 one or two occasions. By means of the analysis of the air in the chamber at 

 the end of each day, however, it was possible to correct for the amount of the 

 leak with great accuracy. 



PHYSIOLOGICAL MEASUREMENTS. 



The same difficulties which attended the making of grosser observations on 

 the subject prevented a thorough series of physiological measurements, such as 

 could be obtained with a subject moving freely about the laboratory. It is very 

 much to be regretted that the observations actually made could not have been 

 amplified and a greater amount of data secured. Fortunately, however, the 

 study of Succi by Luciani was especially complete in observations of this 

 nature, and inasmuch as Succi's fasting experiment lasted for 30 days, it is 

 fair to assume that the data obtained by Luciani could not be greatly amplified 

 by any data secured in an experiment of such short duration as 7 days. 



Measurements of body temperature. In spite of the difficulties of making 

 physiological observations on a subject inclosed in a respiration chamber, it 

 was possible to secure the body temperature of the subject with great accuracy 

 by means of a rectal thermometer, fully described elsewhere. 32 By means of this 

 thermometer, which is on the principle of a bolometer, the variations in 

 electrical resistance of a fine platinum wire inclosed in a pure silver tube and 

 inserted several centimeters in the rectum can be observed at will. While the 

 majority of our subjects have experienced no difficulty in wearing this electrical 

 resistance thermometer for a considerable period of time, the subject of the 

 longer fasting experiments found this difficult and it was only during certain 

 experimental days that he could use the thermometer and insure us normal 

 results. It was deemed inadvisable to urge the use of the thermometer for fear 

 of causing the subject discomfort which might produce abnormal results. In 



32 Archiv f. d. ges. Physiol. (1901), 88, p. 492; Carnegie Institution of Washing- 

 ton Publication 42, p. 156 (1905). 



