150 I. IJIMA : HEXACTINELLIDA. I. 



of the trabecula itself. This indication of life, which I have 

 observed in E. inarshalli as ^vell as in Acanthascus cactus, I 

 interpret as due to protoplasmic contractility. As for a flow of 

 protoplasm, it is not possible, since the trabeculse, though soft, 

 pliant and easily destroyed by pressure, are much too consistent 

 to be with any exactness called fluid. 



Observed iu hardened preparations, tlie substance of the 

 flUimentous trabeculœ is tolerably well stained and dense-looking, 

 being either nearly homogeneous or granulated in varying 

 degrees. The membranous expansions, looked at face on, usually 

 present a somewhat less dense or clearer appearance, apparently 

 due to the thinning out of their substance in forming such areas. 

 Here are seen granules and irregular particles or little streaks, 

 which are scattered either somewhat uniformly or in a manner 

 suggestive of a reticular arrangement (PI. IV, fig. 23 ; PI. VIII, 

 fig. 30). This appearance may be partially the result of the 

 hardening process. A fibrous or streaked appearance is also not 

 infrequently noticeable, generally running parallel with the free 

 edges of the band-like or otherwise membranously developed 

 trabecule. In most such cases, I have convinced myself of the 

 fact that the appearance is due, not to the real existence of 

 differentiated fibers, but to fine wrinkles which are probably 

 produced by contraction ; for, the streaks are not only of very 

 indefinite contour in certain places, but also at the ends are seen 

 gradually to lose themselves in the membrane as it generally ap- 

 pears. The edge-line of the trabeculse is always of simple contour. 

 Sometimes unusually coarse, réfringent and well-stained 

 granules are found in isolated occurrence. These are j)robably 

 the same as those found inclosed in the thesocytes to be described 

 further on. 



