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ME. G. J. ROMANES ON THE LOCOMOTOE SYSTEM OE MEDUSiE. 
normal interval, and when they occur are of the feeblest character. Soon after this 
stage has been reached the systoles altogether cease ; and in a few seconds after they have 
done so the animal fails to respond even to the strongest stimuli ; and this, be it remem- 
bered, is quite as remarkable a fact in the case of Medusse as it is in . the case of the 
higher animals. The time occupied by the whole of this process varies with different 
species ; but it is always very brief, namely (speaking from memory) about fifteen seconds 
to a minute in the case of Sarsia and eighty seconds to two minutes in that of Aurelia 
aurita. But brief as is the time required for chloroform to assert its influence upon 
Medusae, it is long as compared with the time required for its effects to pass off when 
the animal is again restored to normal sea-water. A specimen of Sarsia which has been 
completely anaesthesiated, and so to all appearance perfectly dead, resumes its pulsations 
a few seconds after being again immersed in unpoisoned water. There appears to be a 
relationship, however, between the time required for complete anaesthesiation and that 
required for complete subsequent recovery, for the recovery of Aurelia aurita takes a few 
seconds longer than does that of Sarsia. In all cases the recovery is progressive, the 
first pulsations being very feeble and the periods of diastole prolonged ; but very shortly 
the pulsations resume their normal strength and frequency. The same animal may 
then, of course, be subjected to a repetition of the experiment, and this for an indefinite 
number of times. 
{b) The anaesthesiating effects of morphia are as decided as are those of chloroform. 
I shall confine myself to describing the process of anaesthesiation in the case of Aurelia 
aurita in an extract from my notes : — “ A very vigorous specimen, having twelve litho- 
cysts, was placed in a somewhat strong sea-water solution of morphia. Half a minute after 
being introduced commencement of torpidity ensued, shown by contractions becoming 
fewer and feebler. In one minute the feeble impulses emanating from the prepotent 
lithocyst failed to spread far through the contractile tissue, appearing to encounter a 
growing resistance. Eventually this resistance became so great that only a very small 
portion of contractile tissue in the immediate neighbourhood of the lithocyst contracted, 
and this in a very slow and feeble way. Two minutes after immersion even these partial 
contractions entirely ceased, and soon afterwards all parts of the animal were completely 
dead to stimulation. Recovery in normal water slower than that after chloroform, 
but still soon quite complete. Repeated experiment on this individual four times with- 
out injury.” 
(c) The species I shall choose for describing the effects of strychnia is Cyancea capil- 
lata , which is most admirably adapted for experiments with this and some of the other 
alkaloid poisons, from the fact that, in water kept at a constant temperature, its pulsa- 
tions are as regular as are those of a heart. After Cyancea capillata has been allowed 
to soak for ten minutes or so in a weak sea-water solution of strychnia, unmistakable 
signs of irregularity in the pulsations supervene. This irregularity then increases more 
and more, till at length it grows into well-marked convulsions. The convulsions 
manifest themselves in the form of extreme deviations from the rhythmical contractions 
