On the effects of sulphate of atropia on the nervous system of frogs / by Sydney Ringer ... and William Murrell.

  • Ringer, Sydney, 1835-1910
Date:
[1876-1877]
Catalogue details

Licence: Public Domain Mark

Credit: On the effects of sulphate of atropia on the nervous system of frogs / by Sydney Ringer ... and William Murrell. Source: Wellcome Collection.

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    “pithed and pegged” we mean division of the cord by cutting, and destruction of the brain by the introduction of a piece of wood into the cranial cavitv. We, like Dr Fraser, often obtained strong tetanus from the subcutaneous injection of atropia, but found that his dose (from T^g- to x^Vo of the weight of the frog) usually killed our animals instead of producing the desired result. With a smaller dose, however, namely, from 2oVo> we were more successful. The tetanus in our experiments commenced earlier than in Dr Fraser’s, our average period of onset being 20 hours; in one case it was well marked in 3 hours, whilst in the longest delayed it was 28 hours. With us, too, it lasted for a shorter time, for in one animal it con¬ tinued only eight hours, and never in any instance exceeded five days. We imagine that these differences are due to the time of the year at which the observations were made. In the fol¬ lowing table we give a summary of these experiments:— Table I. Why is the tetanus so long delayed after atropia poisoning ? One writer, referring to Dr Fraser’s paper, says that the paralysis of the motor nerves prevents the tetanic condition of the cord from displaying itself on the muscles, but Dr Fraser himself nowhere makes this assertion, and indeed his cases prove the contrary. This proffered explanation we hold to be erroneous for the following reasons:— I. Bezold and Bloebaum have shown that even with very large doses it is difficult to destroy completely the conducting power of the motor nerves, and it is obvious that as long as their conductivity is in the smallest degree retained, the tetanic condi¬ tion of the cord must produce more or less tetanus of the muscles. II. The onset of tetanus is delayed even in cases in which the dose of atropia is so small as to produce but slight paralysis, and it must be admitted that if the motor nerves are capable of conveying voluntary and normal reflex impressions they can conduct tetanic reflex stimuli. Thus in many of Fraser’s cases there was never complete loss of reflex and voluntary power during the period which elapsed between the injection of the drug and the onset of tetanus. It will be found that of the cases in which he obtained tetanus there were twelve in which