August 15, 1919] 



SCIENCE 



163 



would seem hardly necessary to attribute the 

 perfect marching in the absence of sound 

 signals to any mutual subconscious force pass- 

 ing betwen the men. Would it not be reason- 

 able to infer that in this case the rhythm is 

 sight-transferred? To be sure, in a long 

 straight column any particular squad would 

 not be able to see far down the line, but in 

 getting the time of the step from those some- 

 what in advance of them there would seem to 

 be as much likelihood of the slight error 

 having either sign, so that there would be no 

 accumulation in error back through the 

 column, as occurs in the case of establishing 

 the rhythm by means of sound signals at the 

 head of the column. That there is, in the ab- 

 sence of sound signals, a sway and swing 

 absent at other times, may be solely a result 

 of perfect rhythm, rather than a result of any 

 difference in the marching of any one man. 

 It is conceivable that in a column of men 

 every man would be marching with rhythmic 

 step, and with dash and enthusiasm, and yet 

 there would be no satisfactory swing and sway 

 to the coliunn if the men were in slightest 

 amount out of step. Synchronize their move- 

 ments, and the result becomes immediately 

 rhythmic and inspiring, although each man 

 may be taking the same steps in exactly the 

 same way. 



That a marching column accepts audible 

 signals in preference to visual signals in case 

 both exist is, I should suppose, a matter of 

 common knowledge. The writer had occasion 

 to drill on the grass-covered EUipse at Wash- 

 ington many mornings last summer before 

 the heavy dew had gone. The dominant note 

 caused by marching was not that resulting 

 from the planting of the foot, but rather that 

 from the movement through the heavy wet 

 grass — a sound exactly out of phase with the 

 former which ordinarily, in a small body of 

 men, gives the sound signal for the rhythm. 

 The strenuous West-Pointer who was con- 

 ducting the drill never seemed to realize why 

 he could not keep the men in step at such 

 times. There was a continual wave of chang- 

 ing of step passing back through the column, 

 in. an everlasting but hopeless endeavor to 



make the step coincide with a signal auto- 

 matically and inescapably out of phase with it. 

 Warren Weaver 

 unrversitt of wisconsin, 

 Madison, "Wis. 



SCIENTIFIC BOOKS 



The Elementary Nervous System. By G. H. 



Parker. Philadelphia, J. B. Lippincott Co. 



1919. Pp. 227, figs. 53. 



With characteristic lucidity. Dr. Parker has 

 written the second of the Monographs on 

 Experimental Biology of which Dr. Loeb's 

 "Forced Movements, Tropisms and An.imal 

 Conduct" is the first. Limited by the plans 

 already outlined for subsequent volumes of 

 the series to subject matter " drawn almost 

 entirely from the three simpler phyla of the 

 multicellular animals, the sponges, ccelenterates 

 and the ctenophores," this book is nevertheless 

 an illuminating introduction to the more fun- 

 damental problems of nervous systems in gen- 

 eral. Anatomy and histology are not neg- 

 lected. The author, however, has attacked the 

 subject frankly as a physiologist, by the 

 method of quantitative experimental analysis 

 that in recent years has been revealing a more 

 and more intimate kinship between biology 

 and the maturer sciences of physics and chem- 

 istry. The bibliography at the end of the 

 volume contains one hundred and sixty-six 

 titles, and the author has been exceptionally 

 careful, by frequent references throughout the 

 text, to acknowledge his appreciation of the 

 work of others. Tet, owing to the compre- 

 hensiveness of his own researches, he has been 

 able in the development of his theme to re- 

 view many of his own experiments. In this 

 way, though these reviews are necessarily brief 

 and untechnical, he makes of the reader a co- 

 investigator who shares with him his own 

 keen interest in the problem, his rare skill in 

 devising experiments that are masterfully 

 direct and simple, and who feels the confi- 

 dence in the results that clear-cut worlanan- 

 ship inevitably inspires. 



In an introductory chapter the neuromus- 

 cular mechanisms of the higher animals are 

 analyzed into receptors (sense organs), ad- 



