174 ANIMAL PHYSIOLOGY. 
clamped by a portion of the femur cut off with the muscle, is 
made, on stimulation, to raise a weighted lever which is at- 
tached to a point writing on a 
cylinder moved by some sort of 
clock-work. In this case the 
cylinder is kept stationary dur- 
ing the contraction of the mus- 
Ss cle; hence the records appear 
- as straight vertical lines. 
Fic. 168.—Muscle-nerve preparation, showing For recording movements of 
gastrocnemius muscle, sciatic nerve, an ian : 
portion of femur of frog, for attachment great rapidity, so that the in- 
to a vise (after Rosenthal). 
: tervals between them may be 
apparent, such an apparatus as is figured below (Fig. 169) an- 
swers well, the vibrations of a tuning-fork being written on a 
Fic. 169.—Spring myograph of Du Bois-Reymond (after Rosenthal). The arrangements for 
registering various details are similar to those for pendulum myograph (Fig. 177). 
blackened glass plate, shot before a chronograph by releasing 
a spring. 
Several records may be made successively by more compli- 
cated arrangements, as will be explained by another figure 
later. 
THE APPARATUS USED FOR THE STIMULATION OF MUSCLE. 
It is not only important that there should be accurate and 
delicate methods of recording muscular contractions, but that 
