216 HYATT, 



Growth begins at the approach of spring and the edges 

 of the sheath are split apart by the increasing bulk of the 

 polyzoon, which protrudes between them. The opacity of 

 the sheath has hitherto prevented rnicroscopists from as- 

 certaining the early history of the development of the 

 polypide, and we are obliged to be content with such ob- 

 servations as can be made during the later periods of its 

 life, when it is partly exposed. 



The organs, when the little animal first makes itself 

 visible, are well advanced in growth and the polypide is 

 already capable of retraction and expansion. For a time 

 it floats freely in the water, wafted about by the cilia, 

 which clothe the whole external surface, and increases in 

 size until the sheaths of the statoblast can no longer con- 

 tain it; then, in some appropriate locality, the gelatinous 

 ectocyst adheres to the surface, the cilia are absorbed, and 

 the polypide enters upon a new phase of life as the founder 

 of a community. 



The sides of the sheath and the annulus, although sepa- 

 rated from each other, frequently cling to the bud, and may 

 occasionally be found adhering to its sides even after the 

 colony has attained its full size. 



Besides these floating buds, which might be called free 

 statoblasts, there are others, originating in a similar man- 

 ner, but from the attached or lowermost sides of the cells 

 instead of the funiculus. These remain permanently fixed 

 by their external investment to the endocyst, and, on this 

 account, I have called them fixed statoblasts. They have 

 been described in Plurnatella emarginata and Alcyonella 

 ( Plurnatella) Benedeni by Prof. Allrnan, arid by Dr. Leidy 

 in Plumatella nitida.* 



It may be well to remark here, that the location of the 

 free statoblast in Fredericella is different from what it is 

 in all other genera. After dropping in the usual manner 

 from the funiculus they become soldered to the sides of 

 the parent cells, and being ol the same size, are indistin- 

 guishable from the true, fixed statoblasts. 



The fixed statoblasts found in Plumatella are much 



*Dr. LEIDY. Proc. Philadelphia Acad. Nat. Sciences, Vol. 5, p. 321. 



