SYNCRYPTA SPONGIARUM. 311 



both monads and spheres are ingested by the collar-cells. Neither Dendy 

 nor I have observed any stage suggesting that the l'6/i monads grow in the 

 water to the 7 /i diameter of the many-celled spheres. This growth presum- 

 ably takes place elsewhere and under other conditions ; Vosmaer's obser- 

 vation suggests that it is in the meso^loea of a Clathrinid. It is therefore a 

 remarkable coincidence that Urban has observed uniformly stained spheres 

 of the same diameter, symbiotic (or parasitic ?) in the mesogloea of a 

 Clathrinid, where they multiply by binary fission ; and that Dendy has 

 figured precisely similar organisms from a Clathrinid on tue other side of 

 the world. 



There is some evidence that the Clathrinida? also feed on the monads, and 

 it may be in this way that the new generation of Syncrypta enters the body 

 of a fresh host. Fig. H shows the monads of S. spongiarum (copied from 

 Dendy's fig. 89, of 16 cells) beside fig. I "a foreign body lodged in the 

 lumen of the collar," copied from Robertson and Minchin's fig. 48 (1910, 

 Clathrina coriacea) ; and fig. K is a collar-cell " showing enclosure, . . . 

 perhaps of a parasitic nature" from their fig. 35 (cf. Dendy's fig. 71). 

 Figs. L and M are collar-cells from an Ascaltis cerebrum in iodine and sea- 

 water sketched by me at Naples (probably in the month of June), with the 

 note "chlorophyll granule ? " to fig. L ; fig. M being one of several collar- 

 cells which showed what was presumably an ingested pyrenoid — " a strongly 

 refractive granule, blue with iodine. It gives the appearance of being blue 

 only on the surface. Professor Paul Mayer says it is not starch." 



The monads can enter freely through the pylocytes of the Clathrinids. 

 Clathrina clathrus, alive at Naples, showed dermal pores of 8/tx4/t, 7 /i x 5 fi, 

 or 6/4x6/4. This was in aquarium water, which Minchin has shown 

 (1892c) affects this species; but in his plates (1897) the dermal pores of 

 " Clathrina coriacea" measure mostly about 4/»x3/i, the largest only being 

 9/t x 4 /a (fig. 10) ; in "Clathrina sp." they are 8 /a x 5/4 and 4A/4 x 4A/4. 

 " Clathrina contorta" shows them larger — 11 /t x 8 /i and 15 /a x 6/4. 



Of the 19 pores measured any one would allow the passage of a monad, 

 even of 2 - 2/4, quite freely. None — and this is important — would allow the 

 entrance of the multicellular spheres observed in the flagellate tubes by 

 Vosmaer and myself ; and the spheres were observed by me in C. clathrus, 

 of which Minchin (1892 c) has shown that the osculum closes before the 

 current stops. 



All that can be said as to the possible transformation of ingested monads 

 of 2/4 diameter into the 7/4 red cells of the Clathrinid mesogloea is that the 

 observations do not contradict it. Dendy (fig. 72) shows in a much altered 

 collar-cell a uniformly stained sphere of 3/4 diameter surrounded by a 

 vacuole; a similar body of 4/4 diameter is enclosed in a phagocyte under the 

 collar-cells in fig. 67. He describes in the collar-cells (p. 361) "circular 



