728 DR FllASER ON THE PHYSIOLOGICAL ACTION 



motor nerves, by protecting a portion of the animal from the poison. Such a 



proceeding cannot be avoided by determining the interval which naturally 



elapses between the moment of death and the time at which loss of function 



occurs in these nerves. This interval varies greatly in different classes of animals, 



and also in different individuals of the same species; and, hence, the data which 



have as yet been accumulated on this point are not available for such purposes 



as the present. 



Experiment XXV. 



The sacrum was excised from an average-sized frog, and, in that manner, the lumbar nerves 

 and the abdominal aorta were exposed. The aorta was ligatured above its bifurcation into the 

 two iliacs, and, immediately afterwards, an average poisonous dose of extract was placed in the 

 frog's mouth. In ten minutes, respiration had ceased; but the frog continued jumping about 

 for other four minutes, when it quietly and gradually subsided on its abdomen and chin. Eeflex 

 movements could be excited by irritating the skin anywhere until one hour and seven minutes 

 after the administration ; but, for some time before this, a great increase in the strength of the 

 stimulant was required. The skin of the posterior extremities had now become paler, while 

 that of the body, anterior to the ligature, had assumed a much darker colour than it had before 

 the experiment ; and the exposed heart was found beating twenty per minute, with regularity 

 and in proper rhythm. The brachial nerve was then laid bare, and was found active ; but this 

 condition ceased two hours and eleven minutes from the commencement of the experiment, and both 

 bradiials were then perfectly paralysed,. At this time, weak galvanism applied with closely 

 approximated poles to sections of the spinal cord produced no effect ; but when the lumbar 

 nerves below the ligature were galvanised they caused vigorous contractions of the posterior 

 extremities. On the following morning, this motor nerve activity still remained, in the parts 

 protected from the poison: but the contractions were now feeble, as muscular rigor was com- 

 mencing below the ligature ; and, in a few hours longer, the muscles separated from the circula- 

 tion ceased to contract. The muscles of the poisoned portion, in which the motor nerves had 

 been long paralysed, were still quite flaccid, alkaline and irritable; and rigor mortis did not 

 occur in them until the following day. « 



Experiment XXVI. 



The right iliac artery and the right ischiadic vein were tied in a frog, weighing 620 grains; 

 and five grains of alcoholic extract of physostigma, suspended in thirty minims of distilled 

 water, were injected into the abdominal cavity. In twenty minutes, voluntary movements had 

 completely ceased, there were no respirations, and the frog lay in a perfectly flaccid condition. 

 Fifty minutes after the administration of the poison, the left sciatic nerve was exposed. Very 

 weak galvanism of the nerve-trunk caused contractions of the limb ; and continued to do so, on 

 occasional observations, till two hours and ten minutes from the commencement of the experi- 

 ment, or till fifty minutes after the respirations had ceased. In other fifteen minutes, how- 

 ever, the nerve was found to be completely paralysed. The right sciatic nerve, which had 

 been protected from the influence of the poison, by ligature of the blood-vessels of the limb, was 

 examined in a similar manner. Its motor conductivity continued unimpaired for at least five 

 hours longer than that of the poisoned nerve. 



These are examples of numerous experiments which were undertaken for the 

 special purpose of determining whether Calabar bean has any action on the spinal 

 nerves. They prove undoubtedly that it has the power of destroying their motor 

 conductivity ; but it has also been demonstrated that this is not the cause of 



