NOTES ON THE PHYSIOLOGY OF SPONGES. 315 



Notes on the Physiology of Sponges. 

 By a. P. Bidder, Sc.D., F.L.S. 



(With Text-figures.) 



[Read 6th May, 1920.] 



The two preceding papers allude to some questions in histology and physiology, 

 the further discussion of which seems better placed under a title where they 

 may be expected. 



Note A. — Ceroids (p. 301). 



Minchin's " minute wandering cells" (1897, p. 499) are clearly elements 

 of great interest and importance. As sucli it is convenient that they should 

 have a short and pronounceable name, and I propose the name " ceroids " l'rom 

 the Greek Kepid? (/ee/o/a'So?), which in two of its meanings well describes their 

 form ; the shape when the nucleus is in the middle sufficiently recalling that 

 of a " shuttle*," while the wedge-like shape manifested when the nucleus is 

 terminal may stand for the "cuneus" of seats in a theatre or amphitheatre 

 (PL 24. fig. 7). 



Minchin's description of their origin and history in Clathrina coriacea 

 takes a different aspect when, in 1908 (p. 354, fig. 71), he draws them also in 

 Leucosolenia ; and again with my observation of them, recorded above, as 

 bursting in a swarm from the wall of C. (G.) coriacea. In Dendy's careful 

 drawings (1914, pi. 24 and pi. 2b') there are somewhat similarly shaped objects 

 shown in Grantia compressa : fig. 44 inside an ovum, fig. 80 in a problemat- 

 ical spherical enclosure. 



But my ceroids in G. coriacea measured 4 fi to 5/a long by 0'5 fj. wide, except 

 at the nucleus, which is 1 //, to 1*2 //. in diameter. Minchin's "minute 

 wandering cells/' in the same species, are in his figs. 17, 19 about 7 fi long 

 with nucleus 1*4 //.. Minchin's " minute amcebocytes " in Leucosolenia 

 measure 3 to 5 fi x 1 to 1*5/* (a nucleus is not shown) ; while the objects 

 drawn by Dendy are only 2 fj, x - 3 fi with "nucleus" 0*6 fi. I define the 

 name " ceroid" as applying to the mobile and emigrant cells of G. coriacea, 

 leaving it to the future to determine if truly homologous cells occur in 

 Leucosolenia and Grantia. 



* The first meaning given to Kepicis by Liddell and Scott, following Smith's Ant., is " the 

 rod or comb by which the threads of the woof were driven home " ; but in this they are 

 wrong, and " shuttle " is the true meaning, on the authority of Butcher and Lang (Trans- 

 lation of Odyssey, V. 62) ; Lang, Leaf, and Myers (Translation of Iliad, XXII. 448) ; 

 Edwards (A Companion to Greek Studies, Cambridge, 1916, p. 520), Bliimner (Gewerbe 

 und Kiinste, 1875, i. 134) ; and my friend Professor Henry Jackson, who told me of the 

 error. L. and S. give no Greek word for " shuttle," rightly omitting narovXicos given by 

 Smith. 



