264 MB. r. J. COLE ON the development of 



plate of secretion which I have not seen in any other " cell," 

 unless it is comparable to the rod in the same position seen in 

 fig. 5. Below are two large asters of a comparatively simple type, 

 and of the usual structure and position. As shown in figs. 3 a and 

 6 h, the split secretion-sphere does not always lie in a vacuole. 



The rhabdite-" cell" shown in fig. 5 is lying practically outside 

 the battery, the rhabdites have broken away from the central 

 mass, leaving the latter lyiug in the middle of the " cell." At 

 the base is another mass of secretion, formed doubtless by an 

 antecedent fragmentation of the original sphere. At the apex is 

 a thin transverse rod, perhaps comparable to the curved plate iti 

 fig. 4, which I have not seen in any other " cell." The " plasma " 

 does not completely fill the latter. The rhabdites are here 

 practically ready to be discharged, and to the left are seen several 

 free rods formed by the discharge of an adjacent " cell." 



Figure 6 shows two contiguous " cells " (lying immediately 

 under the surface) from one field. In & we have a stage similar 

 to that in 3 a, except that in the former two small asters are 

 present, each lying in a clear space, w^hilst the splitting of the 

 secretion-sphere has not proceeded so far. In 6 a, however, the 

 splitting has resulted in the formation of two kinds of rhabdites 

 ■ — stout and fine. The latter are still adherent to the residue of 

 the sphere and are the more numerous, whilst the former have 

 broken off, may project through the wall of the " cell," and bear 

 evident traces of their origin from such stages as those figured 

 in 6 & and 3 a. The whole, together with a small aster of 4 rays, 

 lies in a clear space in the " cell," two small asters being em- 

 bedded in the " plasma." 



The " cell " shown in fig. 7 is an almost isolated example of its 

 kind, and no other exactly resembling it was seen *. Empty sacs, 

 however, having faint longitudinal folds, which have been iden- 

 tified by others besides myself as similar bodies that have been 

 discharged, are not uncommon. In the " cell " above, which lay 

 immediately below the surface, the rhabdites were arranged in a 

 definite axial bundle, no small asters were present, there were no 

 clear spaces in the "plasma," and the whole of the secretion had 

 been used up in the formation of the rhabdites — a condition not 

 often seen. This stage may be described as the final one imme- 

 diately prior to discharge. 



* Since writing I have observed others in Prof. Howes' material at the 

 E. College of Science, Lond. 



