SECTION VI. 



DEMONSTRATIONS. 



In the foregoing chapters experiments have been described 

 which the student, either individually or in small groups, can 

 perform for himself, but there are other experiments of equal im- 

 portance from an educational viewpoint, in which, for obvious 

 reasons this is impossible and it is necessary that these be demon- 

 strated. The value of demonstrations of more or less complicated 

 experiments in physiology depends on two factors, first, that the 

 student is familiar with the general technique of the methods em- 

 ployed, and secondly that the precise application and bearing of 

 the results of each experiment are appreciated by him. To stage 

 an experiment with the sole object of demonstrating results is 

 valueless, however important and fundamental these results in 

 themselves may be ; the demonstration becomes of value only when 

 the student knows exactly how the result is obtained and is able 

 to place it in relationship with previous knowledge gained by other 

 methods of study. 



The particular experiments which it may be deemed advanta- 

 geous to demonstrate will necessarily vary, not only in different 

 laboratories, but also from year to year in the same laboratory. It is 

 believed, however, that it will be useful to describe briefly the 

 fundamental experiments that the authors are accustomed to 

 demonstrate to their classes, partly to assist the students to under- 

 stand what is being done, and partly as a guide to others. The 

 experiments that have been selected may also be performed by 

 advanced students and are described in sufficient detail for this 

 purpose. 



The demonstrations are grouped in chapters, each chapter 

 giving in practicable sequence the experiments which can most 

 conveniently be performed on a single animal. 



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