Mental fatigue : a comprehensive exposition of the nature of mental fatigue, of the methods of its measurement and of their results, with special reference to the problems of instruction / by Dr. Max Offner tr. from the German by Guy Montrose Whipple.

Offner, Max, 1864-1932.

Date:: 1911

Credit: Mental fatigue : a comprehensive exposition of the nature of mental fatigue, of the methods of its measurement and of their results, with special reference to the problems of instruction / by Dr. Max Offner tr. from the German by Guy Montrose Whipple. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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$decomposition and recomposition in that of Her- mann). That this using up of material is present in addition to the accmnulation of fatigue-sub stance is shown by the circumstance that, in spite of repeated removals of the fatigue products, the capacity of a muscle that is subjected to repeated stimulation diminishes, and finally reaches zero. Max Verworn (500 ff.), at Gottingen, has given an exact demonstration of this fact for the central nervous system by a celebrated experiment. The blood of a li^n.ng frog was replaced by an 0.8 per cent, gas-free salt solution {i, e., a solution totally lacking in nutritive substances) until the latter circulated instead of blood in the veins of the animal. Violent convulsions were then produced by a weak dose of strychnine, while at the same time the circulation of the neutral salt solution was discontinued. The pow- erful excitation and the activity involved in the violent contractions caused a rapid production of fatigTie-substances. On account of the checking of the salt solution, these substances were not carried away, and they soon induced a condition of non-ex- citability of the nerves (rigor). So soon, however, as these substances were washed away with the salt solution, the excitability returned, though, it is true, it finally disappeared, despite continued flushing out of the poisons. Here, then, is fatigue without fatigue- substances! If now, however, the frog be flushed with oxygenated salt solution, he recuperates, and the condition of excitability is once more restored. Yet, still, after a time excitability again disap- pears, despite continued flushing with the oxygenated solution. Only when the frog has had injected in$