AUTOTOMY OF HYDRANTII OF TUBULARIA. 



175 



bear this out. At the base of the hydranth and at the distal 

 end of the stem, from which the hydranth has been severed, there 

 is no definite arrangement of the cells into ectoderm and ento- 

 derm. The cells seem to lie freely in the chitinous envelop. The 



FIG. i. Sagittal section of Tnbularia hydranth immediately after autotomy. 

 The hydranth had fallen to the bottom of the dish. 



cylindrical or flattened epithelium cells of ectoderm and ento- 

 derm of the normal individual have now assumed a spherical 

 form. In the iron-alum stain, the nuclei appear for a time nor- 

 mal, but later distinct changes, undoubtedly pathological, have set 

 in. There is no indication of an absorption of such cells into 

 the lower portions of the stems as Cast and Godlewski (/. c.} 

 have described for Pennaria. 



