1920] Tai/lur: Newromotor Apparatus in K<II>I<>II x 4:i:! 



S!HI\\S signs of dissolution by a gradual dispersion of its granules and 

 llii' anal cirri libers, with or without their cirri attached, atv at length 

 set free, tlicir spatial relations occasionally remaining unchanged. 

 Can- fill observations during tliis tardy disintegration of cctoplasui, 

 aloni: with tlie explorations by means of the needle, make it. fairly cer- 

 tain that the anal cirri fibers do not lie within the ectoplasm but upon 

 its inner surface, being supported there by a very thin, hyaloplasmic 

 sheath which may be a continuation of or comparable with the hyalo- 

 plasmic matrix in which are embedded the granules of the ectoplasm. 

 The critical focus for a fiber does not appear to be identical with that 

 for the ectoplasmic granules along (below) the fiber. Furthermore, 

 (lie fillers are more or less readily displaced by means of the needle, 

 although when undisturbed they remain adherent to the ectoplasm. 



When set free from all attachments, the anal cirri fibers may be 

 bent variously with the needle (fig. 15). They are then found to be 

 fairly flexible, in no wise brittle and almost wholly irresilient. How- 

 ever. In-fore the ectoplasm has completely dissolved, the fibers are 

 much less flexible and generally recover after being bent. Figures 14 

 and 15 illustrate several permanent shapes into which the fibers were 

 bent by means of the needle. They may adhere to the needle and so 

 be pulled about through the water. They do not long resist dissolution 

 and so disappear usually within fifteen minutes or less time after their 

 exposure to the water. 



Apposed dorsally to the basal plate of each anal cirrus, the corre- 

 sponding fiber is modified into a "fan shaped structure' (Yocom, 1918) 

 which I shall here designate the "anal fiber plate." This small plate is 

 distinctly rectangular (fig. 14), and not oval as figured by Yocom. Its 

 attachment to the fiber proper is secure, as may be readily ascertained 

 by pulling or pushing the fiber about through the water with the 

 needle-point. An interesting and significant feature is its intimate 

 association with the basal plate of the anal cirrus. Figure 14 is a 

 camera drawing of a cirrus in the process of detachment from the 

 "anal fiber plate." It will be observed that the cirrus has rotated 

 90 degrees on its long axis and that the gelatinous extensile basal plate, 

 which is a highly viscous gel, remains attached to the anal fiber plate. 

 This attached condition is rarely found, owing to the readiness with 

 which the basal plate detaches from the anal fiber plate. While 

 attempting to make this drawing with the parts in situ, the separation 

 ensued so readily that I succeeded in outlining only the partial detach- 

 ment as shown in the figure. 



