CENTRAL NERVOUS SYSTEM. 295 



thirds of the total time for rest and refreshment, vet the feat was most 

 difficult to accomplish by reason of the discontinuity in the sleep. 



The changes leading to recuperation needed longer periods than those 

 permitted by the conditions of the experiment. 



Loss of Sleep. — Loss of sleep is more damaging to the organism as a 

 whole than is starvation. It lias been found (Manace'ine) that in young dogs 

 which can recover from starvation extending over twenty days, loss of sleep 

 for five days or more was fatal. Toward the end of such a period the body- 

 temperature may fall as much as 8° C. below the normal and the reflexes 

 disappear. The red •blood-corpuscles are first diminished in number; to be 

 finally increased during the last two days, when the animal refuses food. 

 The most widespread change in the tissues is a tatty degeneration, and in the 

 nervous system there were found capillary hemorrhages in the cerebral hemi- 

 spheres, the spinal cord appearing abnormally dry and anaemic. 



Patrick and Gilbert l have studied the effects of loss of sleep in man 

 (three subjects, young men, observed during ninety hours without sleep). 

 All the subjects gained slightly in weight during the period, but lost this 

 excess in the course of the first sleep following the experiment. The excre- 

 tion of nitrogen and phosphoric acid was increased during the period, the 

 increase being relatively greater in the case of the phosphoric acid. There 

 was a marked tendency to a decrease in the pulse-rate, and some tendency 

 for the body-temperature to fall. During these ninety hours the subjects were 

 tested at intervals of six hours (the tests required some two hours on each 

 occasion), to determine variations in the muscular and mental powers. 



In brief, it may be said that most tests revealed a loss, which early 

 appeared in the reactions of the muscular system, and later in those of the 

 nervous system. In the test for the acuteness of virion (measured by the 

 distance at which the subject could read a printed page illuminated by the 

 light of one standard candle at a distance of 25 cm.) there was, however, 

 an increase in capability in all the subjects. At the end of the experiment a 

 small number of hours of sleep in excess of that customarily taken appeared 

 to bring about a complete restoration of the subject. The disproportion 

 between this amount of extra sleep and the amount lost during the period 

 of experiment is noted by the authors, though it still lacks satisfactory 



explanation. 



E. Old Age of the Central System. 



Metabolism in the Nerve-cells. — Connected closely with fatigue are 

 those alterations both of the constituent nerve-cells and of the entire system 

 found in old age. The picture of the changes in the living cells is that of 

 anabolic and catabolic processes always going on, but varying in their absolute 

 and relative intensity according to several conditions. Of these conditions 

 one of the most important is the age of the individual. In youth and during 

 the growing period of* life the anabolic changes appear within the daily cycle 

 of activity and repose to overbalance the katabolic, the total expenditure of 

 1 Patrick and Gilbert : Psychological Review, 1896, vol. iii. No. 5. 



