254 REPORTS ON THE STATE OF SCIENCE. — 1916. 



allotted to each task. Unfortunately, of course, the actual strain in- 

 volved varies with the occasion, and the matter is further complicated by 

 various other conditions, such as the time and amount of the place for 

 rest and sleep, the adequacy and sufficiency of food, the amount of noise 

 and sensory disturbances generally, and the nervous strain of exposure 

 to fire, and so on. 



It is obvious we must therefore dispense with the hope of obtaining 

 an ideal working day for each military unit. 



All that we can reasonably hope for is that, with the present greater 

 ability to supply reinforcements, we can diminish the strain as well as 

 more frequently replace the actual fighting units ; and it becomes a 

 matter of the greatest urgency that with this ability, and with the 

 growing delicacy of perception in the anticipation of the breaking-point, 

 a greater discretion might be employed to prevent it. 



Now we have two degrees of acute fatigue always coming up for 

 notice. The one is the occasional case which is sent to the rear in a 

 state of collapse. 



The case is often confused with shock, and in some respects it 

 resembles a case of shock : there is extreme pallor of the face, the 

 extremities are cold, and there is a fine muscular tremor. The blood 

 pressure of the brachial artery in such a case is very low, usually below 

 80 mm. Hg, the pulse is thready and the heart sounds are feeble and 

 fluttering. It is, in fact, to be distinguished from shock only by its 

 history and course. 



Now, such a case follows the usual physiological course. Thus, 

 after compensation has been established in the process of strain — i.e. 

 ' second wind ' has been obtained, the heart is relieved, the vessels of 

 the working part are dilated, and the respiratory embarrassment sub- 

 sides — no further trouble may ensue if rest occurs in due course, but if 

 the work is greatly increased, or if it continues too long, the chief 

 organ to give out is the heart, which is working at high speed and at 

 higher pressure to supply the gi'eater need of the working parts. The 

 heart begins to disjolay its weakness by failing to contract completely, 

 the right heart over-loaded begins to show its distress in the laboured 

 breathing of the lungs. The working parts, making the same demand 

 for oxygenated blood, fail to be adequately supplied, owing to the 

 growing weakness of the heart, and the fatigue products beginning to 

 accumulate interfere therefore with the efficiency of the muscles. 



The discomfort under ordinary conditions may become so acute as 

 to make a worker cease his work ; the initiative, however, which drives 

 the soldier on, may so obsess his mind as to render him insensitive to 

 these flags of distress and so he continues to the danger-point. The 

 heart, still labouring on, fails, owing to congestion of the right heart, 

 to get itself supplied with oxygenated blood, and the condition is there- 

 fore aggravated and it undergoes dilatation. At this stage a failure of 

 cerebral supply brings about syncope, the restitution of cerebral 

 function with the horizontal position may even fail to bring back the 

 mental stimulus, but usually only brings into consciousness the acute 

 feeling of helplessness in the body. 



The soldier may then be fortunate enough to be carried straight away. 



