110 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
and then another of the points which have been 
irritated. In such cases it usually dwells longest 
and most frequently on those points which have 
been irritated most severely. 
I think the object of these movements is probably 
that of stinging the offending body by means of the 
urticating cells with which the extremity of the 
manubrium is armed. But, be the object what it 
may, the fact of these movements occurring is a 
highly important one in connection with our study 
of the distribution of nerves in Medusz, and the 
first point to be made out with regard to these 
movements is clearly as to whether or not they are 
truly of a reflex character. Accordingly, I first 
tried cutting off the margin, and then irritating the 
muscular tissue of the bell; the movements in 
question were performed exactly as before. I was 
thus led to think it probable that the reflex centres 
of which I was in search might be seated in the manu- 
brium. Accordingly, I cut off the manubrium, and 
tried stimulating its own substance directly. I 
found, however, that no matter how small a portion 
of this organ I used, and no matter from what part 
of the organ I cut it, this portion would do its best 
to bend over to the side which I irritated. Simi- 
larly, no matter how short a stump of the manu- 
brium I left in connection with the nectocalyx, on 
irritating any part of the latter, the stump of the 
manubrium would deflect itself towards that part 
of the bell, although, of course, from its short length 
it was unable to reach it. Hence there can be no 
doubt that every portion of the manubrium—down, 
