570 MUSCLE-NERVE PHYSIOLOGY 



It is kept in better condition in an atmosphere of oxygen. Test as many 

 of these points as time permits. 



e. Moisten the strip with i per cent, barium chloride. 



/. Mount a section of the oviduct of the turtle. This tube displays 

 a remarkably even and uniform but slow automatic rhythm. 



22. Periodic Contractions of the Rat's Uterus. A splendid preparation 

 of smooth muscle in a warmblooded animal is obtained by splitting the 

 rat's uterus longitudinally, giving one fallopian tube and one-half of the 

 uterus as a preparation. 



a. Mount a rat's uterus-fallopian tube in the Harvard warm chamber 

 and immerse in a bath of oxygenated Ringer's solution at 37 C. Rhyth- 

 mic contractions of a comparatively uniform amplitude will begin 

 promptly and continue through a long interval. 



b. While the preparation is contracting rhythmically add to the 20 

 cc. of Ringer's solution i cc. of .01 per cent, epinephrin. This hormone 

 stimulates the autonomic nerve endings producing inhibition. The effect 

 passes away after a few minutes or on renewing the solution. 



A similar preparation can be made from the uterus of a guineapig, 

 cat or rabbit. Epinephrin stimulates the inhibitory mechanism of the 

 virgin uterus, but produces contraction of the muscle of the gravid uterus. 



23. Ciliary Contractions. Ciliated Epithelium. Make a preparation 

 of ciliated epithelium by cutting out the esophagus of a terrapin or frog, 

 slitting it open longitudinally, and smoothing it out on a cork block. The 

 cilia of this membrane will drive in the direction down the esophagus. Test 

 the rate at which different loads are moved and measure the distance on the 

 preparation as follows: Cut pieces of clean white paper about 4 and 6 mm. 

 square. Select a favorable area on the ciliated surface as long as possible, 

 place the 4 mm. square paper at the beginning of the area, and measure the 

 time which it takes to travel the distance. Measure the speed in terms of 

 seconds per centimeter. Now replace the paper at the point of beginning 

 and load it with small weighed cubes of paraffin. The rate at which the 

 load is carried will slightly increase at first as the load is increased, but later 

 will sharply decrease. Elevate one end of the ciliated membrane and repeat 

 the experiment with different loads so that the cilia will now carry the load 

 uphill. Calculate the work done in terms of gramcentimeters of work per 

 square centimeter of ciliated surface acting on the load. 



24. Rate of the Nerve Impulse. Prepare a muscle-nerve of a large 

 frog with the entire sciatic nerve. Sever the nerve where it leaves the cord, 

 leaving it attached to the fascia. Mount in a moist chamber using two pairs 

 of electrodes. Set one pair of electrodes on the nerve as near the muscle as 

 possible, the other at the extreme end of the sciatic. Take several pairs of 

 simple muscle contractions on the pendulum myograph stimulating in order, 

 i, the long nerve, and 2, the short nerve. The latent periods must be marked 



