406 WORK OF THE PHYSIOLOGICAL STATION AT PARIS. 



we will liave for each attitude of a limb the length shown by each mus- 

 cle visible in the hgure under consideration. We can easily follow 

 upon the series of photographs the phases of the shortening or length- 

 eniug of these muscles — that is to say, their contraction or their relaxa- 

 tion. We may finally trace the curve or change of length of these 

 ditterent muscles according to time, and compare the relations which 

 exist between certain muscular acts and the reactions imparted to the 

 body of the animal. 



As soon as we know the action of the different muscles during the 

 different phases of movement of an animal, we shall have the greater 

 part of the data necessary for understanding the mechanism of loco- 

 motion. Now, this knowledge can not be acquired by simple observa- 

 tion, for the most sustained attention concentrated on the action of a 

 single nmscle, can with difticulty catch the phases of activity and of 

 repose even for the slowest gait. How, then, can we hope to catch the 

 action of all the muscles of the limbs at all phases of a raj)id gait"? 



Such is the general plan for the study of comparative locomotion 

 which I have Just undertaken. This long task is as yet but little 

 advanced, but the results which it promises are worth all the efforts 

 which it will cost. 



V. 



Certain minds value science only for its practical application. To 

 such we may recall what the Physiological Station has already done and 

 show what it may be expected to do. The physician may seek there 

 new means for the diagnosis of certain maladies and for investigating 

 the effects of their treatment; the soldier may study there the proper 

 regulation of marching- so as to diminish fatigue and use to greater 

 advantage the bodily forces; the educator of youth may learn how to 

 logically direct gymnastic exercises; the artist, how to represent more 

 truthfully the scenes that he wishes to depict; the agriculturist, how 

 to use to the best advantage the strength of animals; the artisan, 

 how to more quickly acquire the skill necessary for his professional 

 labors. It seems that the utilitarian side of ])hysiology has up to the 

 present time been the best appreciated. 



But science has also other functions; it gives a lofty satisfaction to 

 the mind by causing us to comprehend the marvelous harmonies of 

 nature. The astronomer who knows how to calculate the movement 

 of the stars, to measure their distance, estimate their masses, and even 

 determine their chemical composition, must have a more lively intellect- 

 ual pleasure than the ordinary contemplator of the stariy vault. There 

 is no doubt that zoology and physiology, mutually elucidating each 

 other, give us a grander conception of the animal kingdom by showing 

 its action in all its beauty. 



I imagine that this evolution of the natural sciences will be effected, 

 as may be said, of itself, by the patient and methodical collection of 



