724 DRS CRUM BROWN AND FRASER ON THE CONNECTION BETWEEN 



of experiments on frogs with varying doses, it was found that Dr Christison's 

 conia invariably produced complete paralysis of the motor nerves before that of 

 the reflex function of the spinal cord ; that Mr Moeson's conia usually produced 

 complete paralysis of the motor nerves before that of the reflex function of the 

 spinal cord in those experiments of the series where the dose was small, and 

 complete paralysis of the reflex function of the spinal cord before that of the 

 motor nerves where the dose was large ; and that methyl-conia produced com- 

 plete paralysis of the reflex function of the spinal cord before that of the motor 

 nerves in those experiments where the dose was small, and complete paralysis 

 of the motor nerves before that of the reflex function of the spinal cord where 

 the dose was large. 



As already mentioned, our chemical examination of the two specimens of conia 

 proved that that of Dr Christison contains a much smaller proportion of methyl- 

 conia than that of Mr Morson. Our physiological examination has confirmed 

 this result; for the action of the latter specimen of conia more closely resembles 

 that of methyl-conia than the former. In other words, the conia containing the 

 smallest proportion of methyl-conia acts most purely as a paralyser of motor 

 nerves. It seems a legitimate deduction from this, that conia altogether free 

 from methyl-conia (i.e., normal conia) will be free also from all spinal action, and 

 will, accordingly, produce paralysis solely by influencing the motor nerves.* 



Our experiments have shown that the lethal activity of Dr Christison's conia 

 is considerably greater than that of Mr Morson's. The comparatively feeble 

 potency of the latter cannot be explained by its containing a large proportion of 

 methyl-conia, for the activity of this substance is about the same as that of Dr 

 Christison's conia ; it may be due to the presence of ammonia. 



Iodide of dimethyl- conium. — When a moderately dilute solution of caustic 

 potash is added to the mixture of iodide of dimethyl-conium and hydriodate of 

 methyl-conia, the latter salt, as stated above, is decomposed, while the former 

 remains in solution, and may be purified by crystallisation from strong aqueous, 

 caustic potash. It is tolerably soluble in hot solutions of caustic potash, but on 

 cooling the solution, it separates in the form of colourless silky needles. It is 

 readily soluble in water, and its composition may be represented by the formula, 

 C 8 H U (CH 3 )NCH 3 I. 



In various experiments, we have administered to rabbits, by subcutaneous 

 injection, doses of half-a-grain, two grains, two grains and-a-half, three, four, 

 and five grains. No obvious effects were produced by half-a-grain, or by two 

 grains ; slight temporary paralysis was produced by two grains and-a-half, and 

 death by three, four, and five grains respectively. It is, therefore, obvious that the 



* We have not as yet succeeded in obtaining a pure specimen of normal conia ; and the 

 quantities of ordinary conia at our disposal have not been sufficient to enable us to attempt a 

 separation of normal conia from methyl-conia. 



