SPONGES. 271 



valuable matter to tlie natural history of sponges, 

 that his name has become European.* 



The chemical nature of sponge is yet a problem 

 to be solved, which may be said of many other 

 animal products. However, something has been 

 done, with a view to solve the difficulty, by Mulder, 

 Crookewit, and Posselt. One of the most remark- 

 able results obtained with regard to the chemical 

 composition of the sponge is that arrived at by 

 Crookewit, who, on analyzing a specimen of Spongia 

 ojficinalis, discovered in it that peculiar substance 

 called fibroin, which Mulder first extracted from the 

 silk of the silkworm, as I stated in the proper 

 place. 



The analyses of this new product do not 

 exactly agree, but they tend to show that fibroin 

 contains 39 proportions of carbon, 62 of hydrogen, 

 12 of nitrogen, and 17 of oxygen. Besides this, 

 sponge contains a certain proportion of phosphorus, 

 of sulphur, and of iodine, which are combined, in 

 some as yet unknown manner, with the fibroin. No 

 albumine or gelatine have been found in sponges, 



* See Ellis "On Corallines," and Grant "On Sponges," in 

 " Edin. Phil. Journ." Also De Blainville, " Actinologie ;" La- 

 mouroux, " Genre des Polypes ;" Dr. Fleming, " British Animals ;" 

 Dutrochet, " Mem. on the Spongilla," in his " Mem. pour servir a 

 1'Hist. des Teg.," etc. ; Bowerbank, in c< Proceed, of the Geol. 

 Soe.," and in " Microscopic Journ., 1841 ;" also " Brit. Ass. Eep., 

 1857." 



