1026 A MANUAL OF PHYSIOLOGY 



commence. As soon as they are well established, and while the 

 contractions are being recorded on a very slow drum, adrenalin 

 solution should be run into the beaker from a graduated capillary 

 pipette in such amount as will make the concentration of it in the 

 beaker i : 1,000,000. Run the adrenalin solution in at a point as 

 far as possible from the uterus ring, so that it does not reach it till 

 mixture has occurred. Mix carefully with a thin glass rod without 

 disturbing the preparation. Note whether the tone of the ring 

 (as shown by its permanent shortening) or the rate and strength of 

 the contractions are increased. If not, remove the solution from 



FIG. 449. CONTRACTIONS OF RABBIT'S UTERUS RING. 



i, Spontaneous contractions in Ringer's solution ; 2, contractions in human 

 serum from a case of persistent high arterial pressure ; 3, contractions in the 

 same serum diluted with its own volume of Ringer's solution ; 4, contractions in 

 Ringer's solution after washing away the serum. Tracings i to 4 were obtained 

 from the same ring ; 5, increase of tone produced in another ring by the addition 

 of a little adrenalin solution to the Ringer's solution, in which the ring had been 

 executing spontaneous contractions. These ceased for a time after addition of the 

 adrenalin, but later recommenced. 



the beaker with a pipette or siphon, replace it by fresh warm 

 Ringer's solution, and start the oxygen current again. While a 

 tracing is being taken repeat the observation, adding a larger pro- 

 portion of adrenalin. Determine in what concentration a distinct 

 effect is produced. This is the basis of a method said to be capable 

 of detecting such minute quantities of adrenalin as can be supposed 

 to be present in blood-serum (Fraenkel). A sufficient number of 

 uterus rings can be obtained from one animal for a considerable 

 number of experiments. 



