A'A R. A. KOCHEIl 



lyiii^- off tlie carotids, etc. After a rest of about three-quarters of an 

 hour to give the animal a chance to recover somewhat from the shock, 

 a canuhi was inserted into the carotid artery, and connected with a 

 manometer for record. The left sciatic nerve was then exposed and 

 stimulated with a faradic current from two dry cells. The secondary 

 coil was placed at eight, later at six. Stimulation was applied at inter- 

 vals, fifteen seconds stimulation was followed by forty-five seconds 

 rest. Stimulation began at twelve o'clock and continued until five 

 P.M. The heart was still beating strongly at the end of the expeiiment, 

 the blood pressure remained fair, and reflexes were obtained through- 

 out b}^ stimulation of the sciatic, both in the right and left leg. The 

 contractions on the right were spasmodic, those on the left — the stimu- 

 lated side, were tetanic. The latter were feeble, and gave all signs of 

 fatigue. The three pairs of dorsal ganglia of the sciatic nerve as well 

 as the lumbar and sacral cord, were removed and placed in the fixing 

 solution. Microscopic examination of the cells and measurements of 

 cells and nuclei from the fatigued and unstimulated side of the cord 

 of the' same animal failed to disclose any difference in morphology. 



Experiment 8. Faradic stimulation of the sciatic nerve of the frog 

 was used in this experiment, the unstimulated dorsal ganglia cells and 

 anterior horn cells of the unstimulated side of the same animal as well 

 as corresponding material from a second resting frog killed at the same 

 time served as control. The two frogs were pithed and placed in a 

 moist chamber. One-half minute stimulation of the sciatic nerve was 

 followed by one minute rest. The electrodes were applied just above 

 the knee at the back. This interrupted stimulation was continued six 

 hours. The muscles showed response by tetanic contractions. At the 

 end of the period the muscles were still irritable. Three pairs of dorsal 

 ganglia corresponding to the sciatic nerve as well as the spina' cord of 

 the same region were taken for study. 



The stimulation produced no changes in the cell morphology that 

 could be detected by a measurement of the size of the cells and nuclei 

 or by study with various powers of the Leitz compound microscope. 



Drug stimulation (strychnine) 



Experiments 9 to I4. Verworn (13) attributed fatigue in nerve cells 

 in part at least to a local asphyxia of the cells due to an accumulation 

 of fatigue substances and an insufficient supply of oxygen. By per- 

 fusing fatigued frogs with oxygenated salt solution, inserting the canula 

 into the aorta, he was al^le to restore irritability of the nerve cells and 

 corresponding response of the muscles in contraction after they had 

 ceased to respond from fatigue. He succeeded in keeping the muscles 

 and nerve responsive to stimulation for mariy hours longer than would 

 ordinarily be the case. In experiments 9 to 14 this method was applied 

 in order to continue stimulation and corresponding nerve exhaustion 

 to a degree not possible by the usual methods. Strychnine in doses of 

 ^ to I of a grain was given in each case by injecting into the subcu- 



