ALTERNATE PHASES IN FOLLICULINA. 8 1 



normal cycle of rhythmic activities characteristic of an entire 

 animal; that is, it proceeded to make for itself a new dwelling 

 with all the developments of form that underlies that architec- 

 tural result. To be sure this new dwelling was small as was the 

 bulk of the anterior half animal that made it and it was not as 

 perfect as normal tubes in the open, but yet it was merely 

 lacking in finish and some perfections of proportion and in no 

 wise deficient in fundamental traits nor more unfinished than 

 many dwellings of whole animals when made in conditions of 

 poor food, etc., incident to long stay in a hanging drop. 



The process of making the tube was continuously observed 

 for nearly one hour during which time a dozen camera lucida 

 sketches of successive phases were made. In making the dwelling 

 the new animal which had regenerated from the anterior part 

 of old one followed the traditional sequences as below described. 



The dwelling or case of Folliculina comprises a sac or attached 

 swollen part and a long tubular continuation which is ornamented 

 by a spiral ridge (Fig. i). The orifice at the end of the tube is 

 completed normally by a very pretty everted lip, made after the 

 spiral part is finished. In this case of dwelling making, the 

 anterior part animal having become attached, proceeded as if 

 entire, assuming for its attached and adjacent areas the same 

 functions as were normally carried on by the old foot which 

 had degenerated within the tube it was imprisoned in. The 

 first action after becoming fastened by the foot consists in con- 

 traction into a form which will be that of the future sac end of 

 the dwelling (Fig. n) and then in this shortened and swollen 

 form the animal secretes from all its general surface, excepting the 

 anterior face that bears the adoral zone, a material which hardens 

 in the water and forms a complete envelope about the animal 

 partaking of its form and thus molding a sac with end open where 

 the anterior face of the animal projects and does not secrete. 

 This secreted sac lies all in one plane and generally has marked 

 bilateral symmetry, since it is attached along one face which is 

 flattened, but in such examples as the present where standing out 

 rather free into the water the sac (Fig. 12) is not so markedly 

 bilateral. 



After the sac is completed it is continued as the tube, but this 



