THE PHYSIOLOGY OF MUSCULAR WORK 200 



experiments upon the isolated muscles of frogs. This has been 

 reflected in the teaching and training of medical students. The 

 underlying idea of the supporters of the school of muscle and 

 nerve appears to be or to have been that a thorough investigation 

 of the properties of two tissues would solve the problem of vital 

 activity. The mystery is greater than ever it was. The day of 

 that school of physiology is passing. A reaction set in some 

 years ago, has not waned, but has steadily gained in strength. 

 Some extremists would maintain that the investigation of isolated 

 muscles and nerves is strictly not physiology ; that a muscle and 

 nerve under such abnormal conditions is pathological and patho- 

 logical to a degree which does not obtain under the ordinary 

 conditions of life. It cannot, however, be denied that such ex- 

 perimental work has its value, for all knowledge is useful if it be 

 properly appraised. Muscle and nerve are not units of life ; the 

 unit is the living organism. Muscular activity under natural 

 conditions is exhibited only by the organism, and under such 

 conditions it should be studied. 



Athletes and the trainers of men and animals for sport have 

 done much for the practical study of the physiology of muscular 

 work. The practice of training is even at the present time ahead 

 of the theory, and each year physiological investigations show the 

 value of the methods introduced by athletes. Experience has 

 been the guide of athletes, and experience is the result of nume- 

 rous physiological experiments upon a large number of men. The 

 diversity and gradation of the muscular exercise involved in the 

 numerous forms of sport render it suitable for all men, young and 

 old, strong and weak. In these and many other respects sport is 

 far superior to physical drill and gymnastic exercises, and as such 

 deserves even more recognition and study than it already receives. 



The main purpose of this article is the physiology of muscular 

 work in man. It will be necessary, however, to glance at some 

 of the elementary facts concerning the structure and properties 

 of muscle considered as a tissue. 



THE STRUCTURE OF MUSCLE 



There are many interesting differences in the naked eye and 

 microscopical structure of muscle, and these must be considered in 

 relation to the various functions of the different kinds of muscular 



