98 Vniversity of Calif oniia Publications in Zoology [Vol. 16 



Average, 50 22 14 



L. — Length of body, without anterior process, in microns. 

 T. — Tliickness of body through the region of the macronucleus, in microns. 

 W. — Width of body at level of the micronueleus, in microns. 



Measurements of the anterior process give a mean value of 9-1 1/a 

 for that part projecting from the body. 



The ectoplasm is a firm, thin and refractive peripheral layer of 

 homogeneous appearance beneath the cuticle. The entoplasm shows 

 under high magnification (2500) no definite structures, but appears 

 to be a more or less homogeneous mass containing small particles of 

 food. So far as could be determined no concretion vacuoles were 

 ever present. 



The whole body is covered by a thin, tough, cuticle of high refrac- 

 tive index. There are no surface marlsings or striations of any kind. 



From the dorsal part of that end pointed anteriorly in locomotion 

 there projects a corlcscrew-like structure, the anterior process (ant. pr., 

 pi. 13. figs. 3, 5). This process makes two turns, is rounded on its 

 anterior end and the terminal portion lies in a plane at right angles 

 to the long axis of the body. Posteriorly, it passes in an irregular 

 path through the outer covering of the body and, gradually dimin- 

 ishing in thiclaiess, passes along in the ventral part of the frontal cap, 

 then dorsal to the oesophagus and finally bending slightly toward the 

 ventral side ends ju.st posterior to the end of the oesophagus. It is 

 clear, highly refractive, homogeneous in appearance, and of marked 

 rigidity. Its path through the entoplasm can be traced as a light line. 

 Its length in all is not quite that of the entire animal ; that part which 

 projects anteriorly from the body is about one-fourth the total length 

 of the process. 



What its function is I cannot say. At least two explanations may 

 be suggested: (1) that it is a residt of transverse fission, and (2) that 

 it serves as a hook whh wliich the ciliate may attach itself to other 

 objects, such as the intestinal epithelium. I have never seen it used 

 in this manner, nor as an organ of offense or defense, nor have I seen 

 the final stages in fission. 



