662 
ME. Gr. J. EOMANES ON THE LOCOMOTOB SYSTEM OF MEDUS2E. 
emanated from a single remaining litHocyst had previously done. On now cutting out 
this localized portion of tissue, the umbrella usually becomes again paralyzed, while the 
portion of tissue which previously animated it may be seen . to continue its contrac- 
tions after the manner of excised lithocysts. I did not pay sufficient attention to the 
number of hours after excision of the lithocysts during which these secondary movements 
continued, to admit of my speaking with confidence on this point ; but, so far as I 
can recollect my numerous experiments with this species, it is certainly not correct to 
say that these contractions ‘ generally ceased after a few moments.’ My impression is 
that they usually last for several days. I agree with Dr. Eimer, however, that, as a 
general rule, the secondary movements in Aurelia aurita are not so persistent as the 
primary ones; and also that in this species, under some circumstances*, insensibility 
to stimulation rapidly supervenes upon loss of spontaneity. This, however, is far from 
being the case with other species — for instance, Cyancea cajaillata will continue to 
respond even to slight stimulation two or three days after it has been completely para- 
lyzed by the removal of its lithocysts, and this even though it be kept in a small jar 
without change of water. Again, if the lithocysts be left in situ and the animal be 
kept in a confined body of water, irritability will continue for days after all the usual 
indications of spontaneity have disappeared. Nevertheless, with slight modifications, I 
have confirmed Dr. Eimer’s experiment of placing different specimens of Aurelia aurita 
under similar conditions, removing the lithocysts of some and not of others, and 
observing that those individuals which had been operated upon died sooner than those 
which had not.” 
This year I have given careful attention to these secondary contractions mani- 
fested by the mutilated swimming-organs of Aurelia aurita ; and as the fact of their 
occurrence will afterwards be found of importance in relation to some peculiar points 
in the physiology of this animal, I shall here detail all the observations regarding the 
subject which I have been able to make. In the first place, the above-quoted state- 
ments with reference to Aurelia aurita have been this year, with one exception, fully 
confirmed by numerous experiments. The one exception refers to my statement as to 
having “ frequently seen these after-contractions as rhythmical (though this is rare), as 
effectual, and as powerful as those which had been previously supplied by the single 
remaining lithocyst.” The word “ rare ” here, as applied to the rhythmical nature of 
these after-contractions, is not sufficiently strong. If I had said “ very ” or “ exceedingly 
rare,” the statement would have been more accurate. For although, so far as I can 
remember, the statement as it stands would apply without correction to Cyancea capil- 
lataf, I have not this year found it to do so in the case of Aurelia aurita. The after- 
contractions of this species are nearly always, as Dr. Eimer describes them, “ irregular 
that is to say, they nearly always occur at uncertain intervals. These intervals are 
* That is, in particular, too high a temperature and want of aeration. 
t I must trust to memory here, because I -was not able this season to obtain a single specimen of this 
species. 
