Page:The American Journal of Psychology Volume 1.djvu/27

 NORMAL KNEE-JERK. 21

eries give a most interesting and important addition to the physiology of the knee-jerk, and of the central nervous system. These results will be reported by themselves later in the paper.

Explanation of the Tables. — Each table is made in three parts ;. the first, headed Knee-Jerk, contains the results of the experi- ments ; the second, headed Extracts from Journal, gives, in brief, the way in which the subject spent the day, and, therefore, an idea of his condition at the time of the examination ; and the third part, headed U. S. A. Weather Observations, reports the condition of the weather in the morning, afternoon and evening. In the first column of the first part of the table, the time at which the examinations were made are set down ; in the second column, the number of experiments made at each time is reported ; in the third is recorded in millimetres the average extent of the knee- jerk as determined by these experiments ; in the fourth are shown the least and greatest knee-jerks got in the examination, and in the fifth is stated, in the number of degrees through which the hammer fell, the least blow by which a recognizable knee-jerk could be obtained. At the bottom of column two the total number of the experiments made during the day is given ; next to this, under column three, is written the average knee-jerk for the day, as determined by the total number of experiments ; by the side of this are noted the extreme variations of the knee-jerk obtained on this day with the blow of standard force, i. e., when the hammer fell through an arc of 40° ; and, finally, under column five, one is- told what was the least blow which was capable, at any time during the day, of producing a visible knee-jerk.