! I02 REPROD UCTION 



pinching up a little of the external coat to do so with fine forceps. 

 Make the arrangements necessary for recording contractions of the 

 ring while it is immersed in a glass cylinder in the bath, as in Experi- 

 ment i, p. 446, but do not divide the ring. Connect the segment to a 

 lever as in that experiment, and make all the arrangements mentioned 

 there. After a longer or shorter interval spontaneous rhythmical con- 

 tractions of the uterus ring commence. As soon as they are well estab- 

 lished, and while the contractions are being recorded on a very slow 

 drum, replace the Ringer's solution by serum, defibrinated blood, blood 



Fig. 467. At ii Ringer's solution was replaced by citrate plasma. At 39 Ringer's solu- 

 tion was replaced by hirudin plasma; at 41 by the corresponding hirudin serum. 



prevented from coagulating by citrate solution (p. 66), or hirudin, or by 

 plasma, and note the effect. Wash away the serum or plasma thor- 

 oughly with Ringer's solution. Replace the Ringer's solution by 

 adrenalin solution (i : 1,000,000). Note whether the tone of the ring 

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

 contractions are increased. While a tracing is being taken repeat the 

 observation, adding a larger proportion of adrenalin. Determine in 

 what concentration a distinct effect is produced. A sufficient number of 

 uterus rings can be obtained from one animal for a considerable number 

 of experiments. 



