482 DR T. R. FRASER ON SOME UNDESCRIBED TETANIC SYMPTOMS 



excite any movement whatever in the anterior extremities, or in any other 

 part of the poisoned region. At twenty-eight hours, the position of the frog 

 was the same as that last described, there being perfect flaccidity and complete 

 motionlessness in the poisoned region, while the posterior extremities (non- 

 poisoned region) were rigidly extended. A touch of the skin anywhere now 

 excited violent tetanus of the posterior extremities, lasting for five seconds ; but 

 no movement occurred elsewhere, and the anterior extremities were perfectly 

 flaccid. To test the condition of motor conductivity in the poisoned region, the 

 right brachial nerve was exposed, and subjected to galvanic stimulation ; no 

 movement of the right anterior extremity was thereby produced, but tetanus of 

 the two posterior extremities invariably followed each stimulation. 



On the third day, the frog was lying on the abdomen, but the chest and head 

 were now raised by the anterior extremities, which had become rigidly flexed. 

 On stimulating the skin, an attack of general opisthotonic tetanus occurred, 

 involving the poisoned as well as the non-poisoned regions. 



In this experiment, the spinal-stimulant action would have been completely 

 masked by the paralytic, if the posterior extremities had not been protected from 

 •the direct influence of the poison. Yet even when this is done, evidence of the 

 spinal- stimulant action will only exceptionally be obtained at so early a stage. 

 Atropia causes paralysis by an action not only on the motor nerves, but also on 

 the sensory (afferent) and on some portion of the reflex apparatus in the spinal 

 cord. In this experiment, two of these causes of paralysis (suspension of the 

 function of the sensory nerves, and suspension of that of some portion of the 

 reflex apparatus in the spinal cord) ceased before the third (suspension of the 

 function of motor nerves) ; for the conductivity of the poisoned motor nerves was 

 still completely suspended when the poisoned spinal cord and sensory nerves had 

 regained their functions. Usually the return to normality occurs much more 

 simultaneously in these different structures. It is still more difficult to obtain 

 evidence in frogs of a spinal-stimulant action occurring soon after the adminis- 

 tration of large fatal doses. Complete paralysis is so rapidly produced that no 

 opportunity is given to the spinal-stimulant action to manifest itself. The evi- 

 dence in support of an early stimulation of the cord is, however, readily obtained 

 in mammals ; for the paralytic effects are never so great as to prevent the mani- 

 festation of the spinal-stimulant action. 



The two already mentioned propositions— namely, that in atropia the amount 

 of paralysing is, in all mammals, greater than the amount of spinal- stimulant 

 action, and that atropia-paralysis is more readily produced in frogs than in 

 mammals — are also sufficient to explain why different effects are produced in 

 frogs and mammals by different doses of atropia. 



When a large fatal dose of atropia is administered to a frog, the predominating 



