Mav 2, 1919] 



SCIENCE 



425 



capricious decision of the mass. He contended 

 that it was a scientific problem, and suggested 

 that if science could establish that a normal 

 man could work up to a given standard with- 

 out detriment to his phj'sical condition and 

 without injury to his health or chance of 

 longevity, the number of hours of a working 

 day could be standardized. In the discussion 

 on the bill in committee he contended that 

 there ought to be a scientific department, 

 working in relation with the Ministry of 

 Health, to decide various matters of a physio- 

 logical nature in relation to capital and labor, 

 including suitable hours of work. We may 

 point out that a large amount of scientific 

 work had been done in this direction, some of 

 which is simimarized in the reports of the 

 Health of Munition Workers Committee, but 

 the subject is complex and physiology is far 

 from having found a complete solution. It is 

 comparatively easy to estimate the amount of 

 energy given out in various kinds of work at 

 various paces, but muscle fatigue is only one 

 and probably the least important element in 

 fatigue. There is in addition the mental ele- 

 ment, which can not be measured, and the 

 nervous element, which it will be possible to 

 measure with difficulty if at all. Nervous 

 fatigue occurs in the initiating and dis- 

 tributing nervous mechanisms of the brain 

 and spinal cord, which are more quickly 

 fatigued than the contracting muscles; con- 

 sequently in the animal body the impulses to 

 activity, springing from the brain, can not 

 bring the muscles far towards complete fatigue 

 before their sources are themselves fatigued 

 and impotent. Though a tired man may refer 

 his tiredness to the muscles, in reality the 

 most severe bodily activity does not produce 

 an.v close approach to complete fatigue of the 

 muscles. The fatigue is of the nervous sys- 

 tem, though its effects may be referred to the 

 muscles. Tlie conclusion of the committee 

 was that the problems of industrial fatigue 

 were primarily, and probably almost wholly, 

 problems of fatigue in the nervous system and 

 of its direct and indirect effects. Another 

 complicating matter is that the human body 

 seems to be adapted to withstand short spells 



of severe labor, broken by longer spells of 

 rest; the point is illustrated b.y the story of a 

 wager between two officers at the front as to 

 the time to be taken in making equal lengths 

 of a trench, each with an equal squad of men. 

 One officer lot his men work as they pleased, 

 but as hard as possible. The other divided his 

 men into three sets, to work in rotation, each 

 set digging their hardest for five minutes and 

 then resting for ten. The second team won 

 easily. Another conclusion — this time in a 

 report by Dr. H. M. Vernon to the same com- 

 mittee — was that the hours of labor ought to 

 be varied between wide limits according to 

 the character of the work performed. This 

 seems the most promising line of inquirj\ — 

 British Medical Journal. 



SCIENTIFIC BOOKS 

 Injurious hisects and Useful Birds. By F. L. 



Washburn, M.A. Philadelphia, J. B. Lip- 



pincott Co. Pp. xviii -|- 453. Price $1.75. 



This little book is one of a series called 

 " Lippineott's Farm Manuals " edited by Dr. 

 K. C. Davis, and now containing about a dozen 

 hand-books on as many phases of agricultural 

 practise. The author of this volume. Pro- 

 fessor Washburn, has for many years held the 

 positions of state entomologist of Minnesota, 

 professor of entomology. University of Minne- 

 sota and entomologist of the Agricultural Ex- 

 periment Station, consequently as an investi- 

 gator and teacher he is in possession of some 

 first-hand knowledge and is posted regarding 

 the work of others. A list of questions at the 

 end of each chapter shows the custom of the 

 teacher. 



The book is divided into twenty-one chap- 

 ters, witli headings as follows : Loss to Agri- 

 culture Due to Insects and Rodents; Farm 

 Practises to Lessen Insect and Eodent In- 

 juries; External Structure of Insects, Orders. 

 Metamorphosis; Collecting and Preserving 

 Insects; Insectides and Spraying; Fumiga- 

 tion; Insects Injurious to the Apple; Insects 

 Aiiecting the Pear and Quince; Plum, Peach 

 and Cherry Insects; Insect Pests of Berries 

 and Grapes; Principal Insects affecting Citrus 



