ALTERNATE PHASES IN FOLLICULINA. 69 



bottom of the house and at the oral or anterior end the remark- 

 able lobes, arms, or flat ribbon-like extensions of the body 

 which have been likened to the ears of a rabbit. These like the 

 rest of the body are exceedingly pliant and almost always in 

 active movement. Where the two arms or lobes arise from the 

 main mass of the body a funnel leads into the interior and ends 

 in a mouth with complex activities. In addition to the longi- 

 tudinal lines of cilia which run on both the outer and inner faces 

 of each lobe there is a very highly organized band of membranells. 

 This starts near the edge of the funnel ventrally on the right side, 

 runs out along the entire inner face of the right lobe almost to 

 its tip, then returns parallel to itself along the dorsal part of that 

 same lobe to the main body, makes a dorsal course around the 

 funnel to the left side and out along the dorsal edge of the left 

 lobe almost to its tip, then back parallel to itself near the ventral 

 edge of the left lobe to the edge of the funnel down which it goes 

 in a spiral of about 2 turns, ending very near the cytostome. On 

 the left ventral face of the exterior of the body there is a definite 

 region which opens and closes as the functional anus. 



While the two phases thus differ remarkably in the high 

 specialization of the adult feeding apparatus as compared with 

 its nearly obliterated condition in the free-swimmer, both phases 

 have essentially the same character of nucleus, namely one long 

 many-lobed moniliform macro-nucleus accompanied by very 

 many minute micro-nuclei. The function of the free-swimmer is 

 not only to transport the animal from one place to another, often 

 for considerable distances, but also to build up the house in which 

 it will live after it has become differentiated into the adult form. 



The method of making the house will be described elsewhere 

 but it consists of a series of activities; first, the selection of, the 

 site; second, the making of the sac or bottom; third, the making 

 of the spiral tube; and finally, the finishing of a lip around the 

 orifice on- top of the tube. After all this is accomplished, the 

 free-swimmer inside the case that it has built, rapidly differen- 

 tiates into the adult form, capable of stretching out of the case 

 and getting its food. It is this adult form which may later 

 dedifferentiate or retrograde into a free-swimmer and break loose 

 and escape from the house and later construct a new house 

 somewhere else. 



