450 University of California Publications in Zoology [ VoL - 19 



shown that the pressure of a very flexible needle when applied to the 

 full width of the body did not alter the normal shape of the animal. 

 Also, when the body was flattened for a few minutes by applying a 

 stiffer needle, or by surface tension, upon releasing the stress the body 

 at once recovered. It was also stated that the pellicle was sufficiently 

 tough to require in dissections the use of needles with fairly stiff, sharp 

 points. Other needles were ineffective. Furthermore, the firmness of 

 the pellicle is sufficient to preserve the normal shape of the body after 

 an incision fully two-thirds its width had been made. The friction of 

 water, induced by the animal's continuous and devious swimming 

 movements, effected no visible change in its shape. Any momentary 

 modification in the shape of E. patella can result only from extraneous 

 pressure. Unlike Paramoecium, which readily forces its way through 

 narrow meshes of silk fibers with distinct constrictions of the body, this 

 animal, owing to the consistency of its pellicle, is of itself unable to 

 alter its form. 



The basal plate and not the fiber plate is the means of secure 

 attachment and support for both the cirri and the membranelles. The 

 rootlets of the component cilia of both membranelles and cirri are 

 imbedded in the gelatinous ectoplasmic basal plate and are only con- 

 tiguous with, but not attached to, the fiber plate. The readiness with 

 which the basal plate becomes detached from the fiber plate and the 

 want of any indications that the ciliary rootlets had been attached to 

 the smooth, clean fiber plate, was previously described. 



The consistency, solubility, size, and shape of the fibers are incom- 

 patible with efficient structures for support. Particularly are the 

 anal cirri fibers frail, readily flexible, and irresilient. They may be 

 pulled in two or bent variously with the needle-point. When entirely 

 free from the ectoplasm they are not resilient and, by means of the 

 needle, they may be readily distorted. They may adhere to the needle 

 and thus be pulled about through the water. Their dissolution is 

 sometimes rapid and usually occurs within fifteen minutes or less 

 after being exposed to the water. It is probable that they are not 

 imbedded in the ectoplasm but lie upon its inner surface, being sup- 

 ported there by a thin, hyaloplasmic sheath. This loose attachment, 

 together with the extensive length and the minuteness of these fibers, 

 indicate that they do not function as supporting structures either for 

 the pellicle, which is of itself distinctly firm and resistant, or for the 

 cirri, whose component cilia are not attached to, but only contiguous 

 with, the basal plate. 



