318 



DR. G. P. BIDDER : NOTES ON THE 

 Fig. 1 . 



Explanation of Text-figures. 



All figures are approximately X 1650 (the scale of Dendy's 1914 plates). 



Figs. 1 A, B, C are from Grantia compressa, fig. 1 D S. raphanus. 



Fig. 1 A. Collar-cells from a sponge gathered at low tide, 27 hours out of the water and 

 replaced in sea-water for 10 hours, flagella moving rapidly. At/ a small portion 

 is drawn of one of the aggregates of excreta which were in the chambers. (Feb. 7.) 

 Note that after their long purging and deprivation of food the collar-cells show 

 perfectly transparent spherules or vacuoles and protoplasm in place of the 

 greenish spherules and granular protoplasm of normal health. Note also that 

 the nuclei are not pear-shaped as described by Minchin, but spherical as 1 have 

 always found theru in life, except that occasionally they are ellipsoidal owing to 

 constriction by the cell-wall in suffocation (see 1895, p. 23, rediscovered by Cotte, 

 1902, see 1903, p. 453). Progressive suffocation is shown in Fig. 1, B. 



Fig. 1 B. a, b, c, d, e. Five successive sketches drawn from the same cell, showing a 

 moving globule of faces in a position which must be just under the iris-mem- 

 brane. From a sponge 2g hours exposed by the low tide, 2 hours in sea-water 

 after gathering. Flagella very active. (Jan. 8.) 



Fig. 1 C. Living collar-cells, showing fasces in a similar position. From a normal sponge. 

 Basal spherules (shaded) are greenish. In the right-hand cell the spherical dotted 

 globule was brown*. (Jan. 20.) 



Fig. 1 D. Amcebocyte with vesicular nuclei and enclosing a ball of fseces, projecting between 

 two collar-cells into the chamber. From S. raphanus, fed with carmine 20 

 minutes, 18 hours' rest, killed osmic acid, decalcified formic acid, not otherwise 

 stained. 



* Comparison with observations made at Plymouth since this paper was written shows 

 that the brown globule was clearly a Syncryptu. 



