56 LOMBARD :
piration had any effect upon the phenomenon. It seemed to make no difference whether the blow fell at the beginning, middle or end of inspiration, or at the beginning, middle or end of expiration. In fact, as far as these experiments gave information, the regular acts of respiration do not reenforce the knee-jerk.
Reneforcement Produced by Asphixia.(?) — The following experiments show that the knee-jerk is not altered by slight changes in the respiratory rhythm, but that it is increased by violent respiratory movements, or the causes which produce them. In the examination made at 8.30 P. M., April 8th, the average knee-jerk was 51 mm. The following experiments were made fifteen minutes later, and in just the same way, except that the blows were delivered at intervals of ten, instead of fifteen sec- onds, the usual rate. The figures show, as in all other cases, the extent of the movements of the foot, resulting from the knee-jerk, in millimetres.
During quiet — 35, 29, 55 — a deep inspiration is taken, and the breath is held for seventy seconds — 41, 44, 45, 49, 55, 72, 100 — breathe again, and at first very hard— 72, 57, 61, 42, 41, 52, 41, 32— another deep inspiration taken, and held seventy seconds — 56, 58, 67, 70, 78, 79, 89 — breathe again, and heavily —80, 59, 64, 5Q f 41, 30.
The first time the breath was held, more than forty seconds elapsed before a material increase in . the extent of the knee-jerk was seen, but during the next thirty seconds, when the endeavor to keep from breathing had become painful, the increase in the knee-jerk was very marked. As soon as the subject
