SECTION OF NAKED-EYED MEDUSAE. 109 



crouching attitude in which this movement termi- 

 nates continues for one or two seconds, after wliich 

 the organ begins gradually to resume its former 

 dimensions. Concurrently with these movements 

 on the part of the manubrium, the portion of the 

 nectocalj^x which has been stimulated bends inwards 

 as far as it is able. The manubrium now begins to 

 deflect itself towards the bent-in portion of the 

 nectocalyx ; and this deflection continuing with 

 a somewhat rapid motion, the extremity of the 

 manubrium is eventually brought, with unerring 

 precision, to meet the in-bent portion of the necto- 

 calyx. I here introduce a drawing of more than 

 life-size to render a better idea of this "pointing 

 action by the manubrium to a seat of irritation 

 located in the bell. It must further be stated that 

 in the unmutilated animal such action is quite 

 invariable, the tapered extremity of the manubrium 

 never failing to be placed . on the exact spot in the 

 nectocalyx where the stimulation is being, or 

 had previously been, applied. Moreover, if the 

 experimenter iriitates one point of the nectocalyx, 

 with a needle or a fine pair of forceps for instance, 

 and while the manubrium is applied to that 

 point he irritates another point, then the manu- 

 brium will leave the first point and niove over 

 to the second. In this way the manubrium may be 

 made to indicate successively any number of points 

 of irritation ; and it is interesting to observe that 

 when, after such a series of irritations, the animal 

 is left to itself, the manubrium will subsequently 

 continue for a considerable time to visit first one 



