i8 4 



PRACTICAL PHYSIOLOGY. 



[XXXI 



by means of the key (K). At first there may be no contraction, 

 but on approximating the secondary to the primary coil a single 

 muscular contraction will be obtained, first with the break shock, 

 and on approaching the secondary nearer to the primary coil, also 

 with the make. The one is called a make and the other a break 

 contraction. Enter in a note-book the results obtained. N.B. In 

 all cases the student should keep an account of the experiment, 

 and especially of all numerical data connected therewith, e.g. : 



Single make and break shocks Du Bois inductorium with 

 i Daniell. 



Compare Ordinary with Helmholtz Arrangement, and tabulate 

 the results as follows, to show the distance of the secondary coil 

 at which mechanical response first occurs. 



The same may be done by applying the electrodes directly to the 

 gastrocnemius muscle, i.e., direct stimulation, that through the 

 nerve being indirect stimulation. 



