Journal of the American Medical Association
of physiology in the Univer¬ sity of Manchester, recently delivered an address on "Health, Fatigue and Repose." Most of the breakdowns in man's life were due to himself, because of ignorance, recklessness, or both. Overwork, without sufficient repair of an organ, whether brain or eye, digestive organs or muscles was the primary cause of fatigue. All the organs of the body could not run at full speed at the same time. Mental fatigue greatly impaired bodily activity, and physical or muscular
... al or muscular fatigue had a dis¬ tinct effect on brain activity. The observations of Dr. Leon¬ ard Hill on the effects of a liberal supply of oxygen in fatigue were most important. Somnolence in churches and chapels seemed on occasion to occur at sermon-time, but it was not in all cases to be attributed to the sermon. The explanation lay rather in the badly ventilated atmosphere, and in the fact that Sunday, though the first day of the week, was to most church-goers the close of the week. The fatigue problem was all important to both the teacher and the child at school. It was well known that certain school subjects produced fatigue sooner than others. The following represented the order of subjects arranged according to difficulty: mathematics (stand¬ ard), 100; Latin, 91; Greek, 90; gymnastics, 90; history and geography, 85 ; French and German, 82 ; natural history, 80, and drawing and religion, each 77. The energy of our nervecells and our muscles exhibited rhythmic variations in the course of the day. In each case they were most energetic between 10 and 11 in the morning, and these periods should be selected for the lesson that was apt to cause most brain fatigue. As to the causes of fatigue, the view that the chemi¬ cal substances in the muscle or in the blood were used up more rapidly than they were replaced was substantially true. That muscular fatigue was partly a chemical process was shown by the fact that if an extract were made from the muscles of an animal that had been fatigued and injected into the muscles of a fresh animal, the muscles of the fresh animal showed phenomena which could not be distinguished from those of fatigue. If the blood-vessels of a fatigued muscle were washed with oxygenated water containing a little com¬ mon salt-a liquid which had no nutritive properties the waste-products were removed. Nothing that could yield energy to the muscles was added, yet the muscle retained its activity.