452 Piof. M'Intosli 07i (he 



muscular fibres, which diverge superiorly and inferiorly; 

 the circumferential region is cellulo-granular, and the tip is 

 granular, with a few palpocils. A cup-shaped form is often 

 assumed by the blunt tip, as the central fibres are emi- 

 nently contractile, and thus give a sucker action to the 

 extremity. In some views the muscular fibres acting on 

 the sucker-tip seem to be separated from the hypoderm of 

 the process. Moreover, in the living animal the very fine 

 palpocils cover the tip like a series of motionless microscopic 

 cilia. Further_, the walls of the papillse have a few con- 

 stricting fibres, which are the chief agents in elongating 

 them. After pressure has continued for a short time various 

 cells, mucous glohules, and granules begin to appear at the 

 sides and palpocils on the summit. Strings of mucus also 

 shoot out, enclosing small bacillary cells. Within the hypo- 

 derm of the tentacle is a well-marked circular muscular coat, 

 surrounding a thick longitudinal layer, which is arranged in 

 regular fasciculi, and possessing a raphe at the attachment 

 of the fibres of the vessels at each pole, that for the artery 

 opposite the papillae being most distinct. 



In the central chamber of the tentacle are two vessels, an 

 afferent and efferent. The afferent blood-vessel is the smaller 

 and lies a little on one side of the pole opposite the papillose 

 mai'gin. Its wall on section presents the peculiar striated 

 appearance seen in the anterior dorsal vessel of the body, and 

 such is probably due to the same longitudinal fibres. Both 

 during life and in the preparations it is firm and elastic, and 

 in contrast with the widely dilated, efferent vessel. The 

 latter is not easily made out unless in good preparations, a 

 suspensory band from the centre (or raphe) of the papillose 

 region being attached to it, and then proceeding, like a 

 membranous septum, to the opposite pole. A series of very 

 distinct transverse mesenteries or dissepiments, again, exist 

 in the tentacle, at regular intervals and almost to the tip of 

 the organ. 



The tentacles are reproduced with considerable rapidity. 

 About the third day after removal the new organs appeared 

 on each side as short blunt processes into which the blood 

 entered. In other specimens they were about twice the 

 breadth of the head, but had not yet begun to develop 

 papillae. A distinct artery and vein are apparent in those 

 about as long as the head, but even though they are three or 

 four times as long no capillary branches are apparent, the 

 blood rushing in by the artery to return by the vein. When 

 only one tentacle is being reproduced the activity in the 

 circulation of the entire (i. e. the old) organ is very great, 



