CHEMICAL CONSTITUTION AND PHYSIOLOGICAL ACTION. 701 



about seven times the relative weight. The symptoms following the paralysis 

 produced by sulphate of atropia would, however, be very different from those just 

 described ; for in place of a gradual recovery to normality, violent convulsive and 

 tetanic symptoms would appear, and probably continue for several days, before 

 perfect recovery took place. This experiment, therefore, shows in the most satis- 

 factory manner that sulphate of methyl-atropium, administered in a dose rather 

 less than the minimum fatal, does not cause any convulsant action in frogs. 



In the next experiment, a dose about the minimum fatal was given. 



Experiment XL. — One-tenth of a grain of sulphate of methyl-atropium was 

 dissolved in four minims of distilled water, and injected under the skin at the 

 right flank of a frog, which weighed 460 grains. Symptoms followed with great 

 rapidity ; for in two minutes, the frog could not jump, and the anterior extremities 

 were extended almost powerlessly at right angles to the body, while the respira- 

 tions were extremely feeble and infrequent. In five minutes, the latter had 

 entirely ceased, and, now, only feeble twitches of the toes could be excited by 

 rather severe irritation of the skin, the limbs being perfectly flaccid and motion- 

 less. In nine minutes, irritation caused no reflex movement whatever, and the 

 cardiac contractions were at the rate of thirty beats in the minute. In twenty- 

 nine minutes, it was ascertained that the motor conductivity of the sciatic nerves 

 was suspended, while idio-muscular contractility was still retained. During the 

 two following days, the state of the frog was the same as that last described. On 

 the fourth day, however, it was impossible to discover any cardiac impulse. The 

 muscles still contracted vigorously when they were directly galvanised, and they 

 continued to do so until the seventh day, when rigor mortis set in. 



We learn from this experiment, that a dose of sulphate of methyl-atropium 

 equivalent to the ^-g^th of the weight of a frog, is sufficient to produce a fatal 

 result. As we have already mentioned, the minimum fatal dose of sulphate of 

 atropia for frogs is about the ^oth or the roVo^h of the weight of the animal, 

 but after such doses death is usually preceded by a stage of tetanus. This stage 

 was entirely absent in the experiment with sulphate of methyl-atropium. 



As, however, it might be supposed that sulphate of methyl-atropium will 

 cause convulsive and tetanic symptoms if it be given in the same relative propor- 

 tion as is required to produce these symptoms with sulphate of atropia — viz., in a 

 dose equivalent to about the i^n^th of the frog's weight — an experiment was 

 performed to meet this supposition.* 



Experiment XLIV. — A solution, containing four-tenths of a grain of sulphate 

 of methyl-atropium, dissolved in five minims of distilled water, was injected 



* The frogs used in Experiments XXXVI. , XXXVII., and XL. had been kept in the labora- 

 tory for more than two months before the performance of each experiment. The convulsive and 

 tetanic effects of atropia appear to be more readily produced in frogs that have been thus kept, than 

 in those recently obtained from their natural habitat. 



VOL. XXV. PART II. 8 U 



