A STUDY IN MORBID AND NORMAL TMIYSIOLOGY. 61 



fourth ventricle, and consequent paralysis by pressure of the vaso-motor centres. 

 The following experiment will serve as an example: — 



. Experiment 53. 

 A moderate sized dog. 



Time. Eect. Temp. REMARKS 



10:45 a. M Opened the skull. 



10:57 102O.5 F. 



11:6 Cut the meJullii. 



11:10 102. G5 Perfect parulysis ; breathing nearly suspendoJ. 



11:12 102.76 



11:18 103 Breulhiug- regular; entire paruly.sis. 



11:27 102.87 



12:15 p.m. 101.75 



12:30 101.5 



12:45 101.25 



1 100.75 

 1:30 100 



2 99.75 



3 97.25 



4:20 97.75 Galvanic current applied to the exposed sciatic nerve slows the pulse, Idood pressure 



not decidedly affected. 



4:40 Par vaguni cut. 



4:45 Current applied to freshly exposed femoral nerve, unless sufiicicntl}' violent to cause 



general tetanus, has no effect upon the blood pressure. 

 5:15 Current applied to a freshly exposed sciatic nerve, result as before; under a very 



violent current the dog showed signs of feeling. 

 6:10 Current again applied ; no result. 



Autopsy. — Section ju.st at tlic jniiotion of jious and medulla, leaving on each side a porticju of ti.'i.sue 

 uncut, a fragment of bone lying upon the cerebellum and pressing it down upon the medulla. The 

 whole of the fourth ventricle occupied with a firm clot pressing upon and separating all the parts. 



The progress of this experiment is very instructive. In beginning, the vaso- 

 motor centre was not implicated, and the bodily temperature began to rise. Sub- 

 sequently a clot formed, and slowly annihilated by pressure the function of the 

 vaso-motor centre. With the progressive vaso-motor partilysis tlic temperature of 

 the body fell, at first slowly and then rapidly, ^yllen, as was proven by experi- 

 mental test, the vaso-motor palsy was complete, the degree of bodily heat was far 

 below the normal. 



In searching for the reason that in rabbits separation of the medulla from the 

 pons is so seldom foUoAved by an increase of the animtil temperature, paralysis of 

 the vaso-motor centres by direct injury, shock, or hemorrhagic pressure at once 

 suggests itself. The rabbit is so small an animal that the distance between the 

 space assigned by Owsjannikow as containing the vaso-motor centre and the border 

 of the pons cannot be more than a tenth of an inch. It is therefore very evident 

 that to avoid wounding or influencing the vaso-motor centre, in dividing the medulla 

 high up, is in the rabbit an exceedingly difficult and indeed almost impossible task. 



In conclusion, the following propositions may be considered as expressing the 

 demonstrations of the preceding experiments upon the effect of section of the 

 medulla on animal temperature. 



