CHEMICAL CONSTITUTION AND PHYSIOLOGICAL ACTION. 717 



Mr Morson's conia, dissolved in four minims of distilled water, under the skin at 

 the right flank of a frog, weighing 140 grains. The effects were very speedily 

 produced ; for in less than two minutes, the frog was quite unable to jump, and 

 a decided degree of general paralysis was present. In four minutes, some stiff- 

 ness was present in the anterior extremities and the fingers, causing the latter to 

 be continuously and stiffly elevated until eight minutes after the poisoning. At 

 nine minutes, the frog was in a flaccid state, but, still, somewhat vigorous 

 movements were spontaneously made in the posterior extremities. These 

 consisted at first of extension and flexion movements of a normal character ; 

 soon, however, they became spasmodic, the extension being prolonged; and, at 

 fourteen minutes, they assumed an almost tetanic character, extreme extension 

 being maintained on each occasion for nearly two seconds. In twenty-five 

 minutes, the spontaneous movements of the posterior extremities were extremely 

 feeble, and in thirty minutes, they altogether ceased. In thirty-five minutes, the 

 frog was perfectly flaccid and motionless, and irritation, even of a severe char- 

 acter, failed to excite any reflex movement whatever. The heart was now con- 

 tracting in normal rhythm, at the rate of twenty-four beats in the minute. 



On the following morning, the frog was dead and in rigor. In this experi- 

 ment, the dose (equivalent to the 4-jtyth of the frog's weight) was considerably 

 above the minimum fatal. Our experiments have shown that in frogs, as in 

 mammals, this sample of conia is much less active than that of Dr Christison, 

 for the smallest dose which we have found to produce death is equivalent to the 

 ^-yth of the weight of the frog used. 



The last experiment shows that after a fatal dose of Mr Morson's conia the 

 predominant symptoms are those of paralysis. We shall now describe some 

 experiments performed for the purpose of determining by what action or actions 

 this paralysis is produced. 



Experiment LXXI. — We ligatured the blood-vessels in the right thigh of a 

 frog, weighing 112 grains, and, immediately afterwards, injected one-tenth of a 

 grain of hydrochlorate of Mr Morson's conia, dissolved in five minims of distilled 

 water, under the skin of the left flank. Complete general paralysis was quickly 

 produced in the poisoned regions. In twenty-seven minutes after the injection, 

 irritation of the skin caused active and apparently tetanic reflex movements of 

 the right posterior extremity, but it failed to cause any movement in the parts to 

 which the poison had access. In one hour, the left sciatic nerve was exposed, 

 and subjected to galvanic stimulation; with the result, that no movement what- 

 ever was thereby excited in the left posterior extremity, or in any poisoned part, 

 while pretty active reflex movements were excited in the right posterior ex- 

 tremity. This condition continued until one hour and twenty minutes after the 

 injection, but at this time the reflex movements that were excited in the right 

 posterior extremity were extremely feeble. In one hour and thirty-five minutes, 



VOL. XXV. PART II. 9 A 



