ALTERNATE PHASES IN FOLLICULINA. 79 



tether, and came to swim entirely around the end of the tube, 

 pulling its cord with it till it became wound up like any larger 

 animal so tied (Figs. 10 and u). Fig. 10 shows the result of an 

 excursion about the end of the tube in which the string was 

 drawn out very fine and long, but later the animal relaxed and 

 ceased to swim vigorously so that the string shortened and 

 thickened somewhat. Its elasticity pulled the body back toward 

 the tube. The effete mass within the tube still seemed alive on 

 the surface at 9:25 as it had myoneme bands, and cilia that 

 caused it to revolve, but by 10:32 it had come to rest. At 10:40 

 (Fig. n) the animal ceased to struggle and now having spent the 

 normal time of a free-swimmer in the swimming activities thus 

 carried on by the anterior part with the limitations of tethering 

 to the imprisoned posterior part, the internal conditions of 

 fixation and tube building had become ripe for expression. The 

 base of the external moity flattened out on the tube surface and 

 acquired attachment to the tube after the manner of a nascent 

 foot, while at the same time breaking off the long-lasting tether 

 or strand that had held it to the posterior moity within the tube. 

 Of the old animal was now left the anterior part which proceeded 

 to make a new dwelling on the outside of the old tube (Fig. 12), 

 the swollen posterior part within the old tube which became more 

 and more a rounded dead mass to be destroyed by protozoan 

 scavengers and the slender connection string or middle of the 

 old body w T hich partly inside and part outside the tube soon was 

 lost to view, as if disintegrated or eaten by scavengers. 



The fate of the dead posterior was as follows: A rounded 

 mass (Fig. 12) containing portions of the original macro-nucleus 

 was attacked by protozoa which forced themselves against it 

 and indented it as if it were jelly-like with more firm exterior 

 though the original myonemes and colored bands had dis- 

 appeared. At 11.53 the scavengers entered into the original 

 foot end of the mass which now had become liquified or dis- 

 integrated where attacked. At I o'clock the mass was broken 

 up into fine granular matter (Fig. 13) scattered about by the 

 movements of thirteen scavengers and into certain refractive 

 shells, apparently representing lumps of the macro-nucleus of 

 greater firmness eaten out on one side by the scavengers which 



