' 48 Anatomy of Sagartia ScMlleriana [No. 1, 



moving about between tbe bases of tbe otlier tentacles. The least 

 touch with a solid object of any part of the body, or even an unusual 

 movement of the water, or the sudden direction of the sun's rays 

 against the animal instantly effected its sensitiveness, the effect being 

 a total or partial contraction of the body. At this act a quantity of 

 water was emitted, and generally a few acontia were ejected from the 

 cinclides of the collar, this being done with such a force, as to make 

 the acontia rise nearly two inches in a perpendicular direction. They 

 usually remained for a few moments in the extended position, and 

 were then gradually rolled up in a closely coiled spiral line and re- 

 tracted. Seldom were there any acontia seen to issue from any other 

 part of the column. According to the magnitude of the disturbance, 

 from one to about five minutes elapsed before the animal, when it 

 had once entirely closed the disk, expanded again. 



After the first ten days, the specimen gradually lost somewhat of 

 its high sensitiveness ; it almost constantly remained expanded, but 

 the tentacles were much less active than before, and it required a 

 rather forcible touch to induce the animal to retract them. In a 

 similar manner, the expansion of the body, or the unfolding of the 

 tentacles was remarkably slow, though the animal would not volun- 

 tarily remain closed longer than five or six minutes. Other specimens, 

 however, which also partially lost their original sensitiveness, would 

 remain closed for several hours ; some of them did not expand their 

 tentacles, even for many days, at least not in the day time. 



The acontia were always first discernible to begin their movements 

 near the centre of the base, proceeding towards the periphery, then 

 rising along the wall of the column, till they met a cincUs, through 

 which they were ejected ; they did not, however always rise as high as 

 the collar. When they came in contact with a foreign object, they 

 attached themselves so firmly, that they had to be removed with force. 

 This attachment is, as I have already stated, undoubtedly due to the 

 serrated or bearded ecthorcea of their cnidce which are of consider- 

 able length. The ejection of the acontia is almost momentanous, but 

 the retraction sometimes extends over 8 or 10 minutes, or even 

 longer ;-in a perfectly healthy animal for about three minutes. When 

 the acontium is retracted within the body, it again usually remains 

 lying for sometime along the wall of the column, or is coiled up at the 



