no 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 wdiich 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 Medusae, 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 cuttino^ off the marg^in, and then irritatino^ 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 oft* 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 wdiat 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, 



