232 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
rence of a gradually increasing spasm, which differs 
from a normal spasm in the respects already de- 
scribed under strychnia. In all the species both of 
Sarsia and Tiaropsis, the manubrium and tentacles 
are retracted during exposure to this poison. 
Remarks. 
The above comprises all the poisons which I have 
tried, and I think that all the observations taken 
together show a wonderful degree of resemblance 
between the actions of the various poisons on the 
Medusze and on the higher animals—a general fact 
which is of interest, when we remember that in 
these nerve-polsons we possess, aS 1t were, So many 
tests wherewith to ascertain whether nerve-tissue, 
where it first appears upon the scene of life, presents 
the same fundamental properties as it does in the 
higher animals. And these observations show that 
such is the case. When the physiologist bears in 
mind that in Sarsia we have the means of testing 
the comparative influence of any poison on the 
central, peripheral, and muscular systems respec- 
tively,* he will not fail to appreciate the signifi- 
cance of these observations. In reading over the 
whole list he will meet with an anomaly here and 
* The method of comparison consists, as will already have been 
gathered from the perusal of the foregoing sections, in :—first, 
stimulating the tentacles, and observing whether this is followed 
by such a discharge of the attached ganglion as causes the bell to 
contract ; next, stimulating the bell itself, to ascertain whether 
the muscular irritability is impaired; and, lastly, stimulating 
either the tentacles or the bell, to observe whether the reciprocal 
connections between tentacles, bell, and manubrium are uninjured. 
