218 JELLY-FISH, STAR-FISH, AND SEA-URCHINS, 
pulsations supervene. This irregularity then in- 
creases 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 so characteristic of 
Cyanzea capillata. Instead of the heart-like regu- 
larity with which systole and diastole follow one 
another in the unpoisoned animal, we now have 
periods of violent and prolonged systole resembling 
tonic spasm; and when the severity of this spasm 
is for a moment abated, it is generally renewed 
before the umbrella has had time again to become 
fully expanded. Moreover, the spasm itself is not 
of uniform intensity throughout the time it lasts; 
but while the umbrella is in a continuously 
contracted state, there are observable a perpetual 
succession of extremely irregular oscillations in the 
strength of the contractile influence. It is further 
a highly interesting fact that the convulsions are 
very plainly of a paroxysmal nature. After the 
umbrella has suffered a prolonged period of con- 
vulsive movements, it expands to its full dimensions, 
and in this form remains for some time in a state 
of absolute quiescence. Presently, however, another 
paroxysm supervenes, to be followed by another 
period of quiescence, and so on for hours. The 
periods of quiescence are usually shorter than are 
those of convulsion; for while the former seldom 
last more than forty seconds or so, the latter may 
continue uninterruptedly for five or six minutes. In 
short, Medusze, when submitted to the influence of 
strychnia, exhibit all the symptoms of strychnia 
