ME, G. J. EOMANES ON THE LOCOMOTOR SYSTEM OE MEDUSAE. 
739 
assume a paroxysmal nature — the convulsions consisting of strong shudders and frequent 
spasms with occasional intervals of repose. 
In the case of Tiaropsis diademata the action of strychnia is very similar, with the 
exception that there is no continuous spasm, although occasional ones occur amid the 
twitching convulsions. After a time, however, all convulsions cease, and the animal 
remains quiescent. While in this condition its reflex excitability is abnormally 
increased, as shown by the fact that even a gentle touch will bring on, not merely a 
single responsive spasm, as in the unpoisoned animal, but a whole series of successive 
spasms, which are often followed by a paroxysm of twitching convulsions. The condi- 
tion of exalted reflex irritability is thus exceedingly well marked. Recovery in normal 
water at this stage is rapid, the motions being at first characterized by a want of coor- 
dination, which, however, soon passes off. 
§ 5. Veratrium. — In Sarsia the first effect of this poison is to increase the number 
and potency of the contractions; but its later effect is just the converse, there being 
then prolonged periods of quiescence, broken only by very short swimming-bouts 
consisting of feeble contractions. The feebleness of the contractions gradually becomes 
more and more remarkable, until at last it is with great difficulty that they can be 
perceived at all ; indeed the progressive fading away of the contractions into absolute 
quiescence is so gradual that it is impossible to tell exactly when they cease. During 
the quiescent stage the animal is for the first time insensible both to tentacular and to 
direct stimulation of the contractile tissues. That the gradual dying out of the strength 
of the contractions is not altogether due to the progressive advance of central paralysis, 
would seem to be indicated by the fact that contractions in response to direct stimu- 
lation of the contractile tissues are no more powerful at any given stage of the poisoning 
than are either responses to tentacular stimulation or the spontaneous contractions. 
Still, as we shall immediately see, in the various species of Tiaropsis , irritability persists 
after cessation of the spontaneous contractions. In Sarsia the nervous connexions 
between the tentacles and polypite, and also between the tentacles themselves, are not 
impaired during the time that the bell is motionless ; and even when the irritability 
of the bell has quite disappeared as regards any kind of stimulation, the polypite and 
tentacles will continue responsive to stimuli applied either directly to themselves, or 
to any part of the nervo-muscular sheet of the bell. 
The convulsions due to the action of veratrium are well marked in the various 
species of the genus Tiaropsis. They consist of violent fluttering motions without any 
coordination; but there are no spasms, as in the case of strychnia-poisoning. After 
the convulsions have lasted for some time, a quiescent stage comes on, during which 
the animal remains responsive to stimulation, though not abnormally so. Recovery in 
unpoisoned water is rapid, the movements being at first marked by an absence of coor- 
dination. 
§ 6. Digitalin. — The first effect of this poison on Sarsia is to quicken the swimming- 
motions, and then to enfeeble them progressively till they degenerate into mere spasmodic 
MDCCCLXXVII. 5 L 
