10 ART. 5. — N. YATSÜ : 



The spindle body consists of a thin cell membrane with 

 distinctly fibrous contents. The fibres themselves are in a majority 

 of cases arranged in a single bundle parallel to one another, and 

 converging toward either extremity (PI. L, Figs. 10, 11), but 

 in some instances there have been observed two bundles, so 

 arranged as to form an angle with each other (PI. L, Fig. 7 a) : 

 or in rare instances three bundles are present, arranged like 

 the sides of a triangle (PI. I., Fig. 7 b) ; finally there are those 

 in which several bundles aj)pear running in various directions 

 (PL I., Figs. 7 f, g). Sometimes a bundle of fibres is bent 

 within the membrane (PI. I., Fig. 7 d). Rarely only a fragment 

 of a bundle is found (PI. L, Fig. 7 e). The shape of the 

 spindle bodies, as just described, depends upon the length and 

 arrangement of the fibres. There are also modifications in the 

 mode of combination of fibres with one another : when they are 

 compact they assume the normal spindle shape, while when 

 loosely arranged at one or both ends the bundle does not taper 

 but the ends of the fibres stand widely apart (PI. I., Fig. 7 g). 

 The fibres, it should be stated, are best seen in fresh material 

 just taken out of a living specimen, or in formalin preparations 

 stained with acidulated methyl green. Under this treatment the 

 fibers become somewhat loose and hence more distinct, staining 

 light green with a darker tone in the middle. In favorable pre- 

 parations treated in the same way, a series of fine easily stained 

 refractive granules can be seen arranged on the equatorial surface 

 (PI. I., Figs. 8 a, b, c) as observed by Com in Phoronis. These 

 granules cannot be taken as nuclei, since they are not demon- 

 strated by any other method. The fibres in the living state 

 give evidence of a, great plasticity : in fixed material, on the 

 other hand, they appear stiff and brittle. Their behavior toward 



