January 9, 1914] 



SCIENCE 



53 



tors, so as to form a connected account of 

 the working of living things. 



As to the actual pedagogical methods by 

 which we are to fulfill these requirements, 

 it will be convenient to consider, first, the 

 practical, and secondly, the didactic in- 

 struction. A thorough training in the 

 methods of accurate observation, as applied 

 to living things, must be the first step in 

 the physiology course, for even granted that 

 the student may have graduated in experi- 

 mental physics, it will still be necessary for 

 him to become familiar with methods bj' 

 which to control and simplify the variable 

 and complicated factor that the existence 

 of a living tissue now introduces into his 

 experiment. The experiment in physics is 

 one in which everything is more or less con- 

 trollable, a result once obtained being read- 

 ily repeated; whereas in physiology a dis- 

 turbing element is constantly present, for 

 the physiological properties of the living 

 object, whose movement or other function 

 we are examining, may alter from time to 

 time on account of vital processes over 

 which we may not have any known means 

 of control. 



There are, I believe, no physiological ex- 

 periments more suitable for this prelimi- 

 nary teaching than those on the nerve- 

 muscle preparation of the frog. The ac- 

 tual physiological truths which the student 

 may learn by doing these experiments are 

 certainly not of much importance, at least 

 from the medical standpoint, but the facil- 

 ity in accurate experimentation which he 

 thereby acquires, as well as the ability to 

 use his results for inductively drawing 

 general conclusions, is essential to his fur- 

 ther progress. 



There is one other feature of these ex- 

 periments that is of great value from the 

 pedagogical standpoint, namely, the possi- 

 bility of grading them with regard to com- 

 plexity. In a few weeks the experiment 



may pass from the recording on a station- 

 ary drum of the degree of muscular con- 

 traction resulting from electric stimuli of 

 varying strengths to the determination of 

 the rate of transmission of an impulse along 

 a nerve. When the student has acquired 

 such technical facility that he can repeat- 

 edly obtain the same results in this experi- 

 ment, he may be considered as competent 

 to proceed with the more complicated ex- 

 periments necessary to elucidate the funda- 

 mental truths of physiology. 



The experiments on nerve-muscle being 

 thus largely of a preliminary nature, the 

 time occupied by them should not be un- 

 duly prolonged ; sixteen sessions of two 

 hours each are certainly adequate. 



From such work to the study of the heart- 

 beat in frogs and turtles is a natural step, 

 the experimental technique being much the 

 same, but greater care being demanded in 

 the handling of the object under investi- 

 gation. But another element now enters 

 into the work, for the conclusions which 

 may be drawn froni the experiment come 

 to be of great importance in themselves, 

 and fundamental physiological truths con- 

 cerning the nature of the heart-beat begin 

 to unfold themselves to the observing stu- 

 dent. He begins to feel that he is building 

 up his fund of physiological knowledge at 

 first hand, and he gradually comes to take 

 a real interest in finding out, by consulta- 

 tion with his text-books, to what extent his 

 observations and conclusions conform with 

 those that are generally accepted. To en- 

 courage the spirit of independent investi- 

 gation, and to add interest to the work, it 

 is advisable, after a sufficient number of 

 experiments has been performed, to devote 

 a session or so of the class to a symposium 

 in which the results obtained in the experi- 

 mental work are collated and their signifi- 

 cance discussed. For this purpose, each 

 student should be required to prepare in 



