228 



PRACTICAL PHYSIOLOGY. 



[XLIIL 



later than the other. The distance between the two indicates tlie 

 time taken by the contraction to pass from the one lever to the 

 otlier. Test the effect of cold normal saline. 



Fia. 150.— Marey 3 Registering Tambour. Metallic capsule, T, covered with thin indiS' 

 rubber, and bearing an aluminium disc, which acts on the writing-lever, H. 



3. Thickening of a Muscle during Contraction. 



(a.) Arrange a Marey's tambour to write on a pendulum-myograph (fig. 

 150). 

 (6.) Fix Marey's pince mr/ographigue (fig. 151) so as to compress the 

 adductor muscles between the thumb and the 

 metacarpal bone of the index-finger, keeping the 

 two arms together with an elastic band. Or use 

 a pair of toy bellows, to the arms of which plate- 

 like electrodes are fitted and connected with bind- 

 ing screws. Keep the handles of the bellows 

 pressed upon the adductor muscles by means of 

 an elastic band. Connect the receiving tambour 

 of the pince or the nozzle of the bellows with 

 the recording tambour, introducing a valve or 

 T-tube with a screw clamp into the connecting 

 elastic tube, to regulate the pressure of air within 

 the system of tubes. 



('•.) Arrange an induction machine with the 

 trigger-key of the pendulum-myograph in the 

 ])nniary circuit, and the pince or bellows in the 

 secondary. Take a tracing. The time relations of the contraction are de- 

 termined in tlie manner already stated (Lesson XXXV IL). 



Fig. 151.— ilarey's Pivce Afyo- 

 (jraphique, as made by 

 Verdi n. 



4. "Wild's Apparatus consists of a glass cylinder made by inverting the 

 neck-end of a two-ounce phial. The neck is fitted with a cork, the upper end 

 is open fig. 152, B). A wire connected with a key (K') short-circuiting the 

 secondary coil ot an induction machine perforates the cork. Arranged above 

 is a light lever (L) provided with an after-load (a/), and moving on an axis, the 

 short arm projecting over the mouth of the jar. The whole arrangement is 

 fixed to a platform (P), with an adjustable stand (S) bearing the fulcrum of the 

 lever and the after-load. The cork must be renewed with each new drug used. 



(a.) Dissect out the gastrocnemius, divide the femur with the gastrocnemiue 



