468 DR T. 11. FRASER ON SOME UNDECSRIRED TETANIC SYMPTOMS 



of curara (wourali) frogs may remain for lengthened periods in a state of absolute 

 motor paralysis, with the cardiac action greatly impaired, and nevertheless per- 

 fectly recover without the occurrence of the slightest degree of abnormal activity 

 of the reflex function. Professor Vulpian has recently shown that iodide of phos- 

 phethylamine may likewise produce in frogs complete temporary paralysis, yet 

 this is not succeeded by any spasmodic symptoms.* In many experiments, also, 

 which I have made with physostigma — one of which is described in a paper com- 

 municated to this Society! — complete motor paralysis and great diminution of the 

 cardiac action were produced, yet the animal gradually recovered therefrom, with- 

 out any symptom of exaggeration in the reflex activity having been observed. 

 Similar evidence may be accumulated from many other sources; but it is sufficient 

 to mention an interesting experiment by Vulpian, which has a direct bearing on 

 the question. That eminent physiologist ligatured the aorta at its origin from 

 the heart of a frog, so as completely to stop the arterial circulation. In the course 

 of a few hours, the excitability of the spinal cord was suspended, and, soon after, 

 the conductivity of the motor nerves was considerably impaired. The frog pre- 

 sented all the phenomena of death ; for although the heart still continued to con- 

 tract, it was unable to propel any blood. The ligature was then removed, and the 

 circulation became re-established. By-and-by, respiratory movements reappeared ; 

 in one or two hours, reflex contractions could be readily excited, while voluntary 

 movements were freely executed ; and, soon after, the animal regained all its 

 suspended functions. Yet, although the recovery was established by gradual stages, 

 no symptoms of exaggerated activity of the reflex function were observed. J 



It is unnecessary to discuss this hypothesis further, especially as sufficient 

 evidence will be adduced, in this and the following Section, to demonstrate that the 

 convulsant effects of atropia are caused by a direct action on the nervous system. 



In the attempt to differentiate the structures on whose affection these effects 

 depend, I have considered the possibilities of their being dependent on the muscles, 

 on the efferent (motor) nerves, on the afferent (sensory) nerves, on the spinal cord, 

 or on the encephalon. 



In the first series of experiments, the atropia was prevented from reaching 

 certain limited regions of the body, while it had access to all other regions. 



Experiment XLIV. — The blood-vessels were ligatured at the upper third" of 

 the right thigh of an active male frog, weighing 272 grains ; and immediately 

 afterwards a solution containing one-fourth of a grain of sulphate of atropia, 

 in four minims of distilled water, was injected under the skin of the left flank. 

 In the course of two hours voluntary movements had ceased, and a state of 

 motionless flaccidity was produced. 



* Archives de Pliysiologie Normale et Pathologique, 1868, p. 472. 



-J- Transactions of the Royal Society of Edinburgh, vol. xxiv. part iii. p. 743. 



I Lecons sur la Physiologie Generale et Comparee du Systeme Nerveux. Paris, 1866, p. 457. 



