1885.] Chemical Composition of Cartilage in Invertebrates. 75 



January 15, 1885. 



THE TREASURER in the Chair. 



The Presents received were laid on the table and thanks ordered for 

 them. 



The following Papers were read : — 



I. " On the Chemical Composition of the Cartilage occurring 

 in certain Invertebrate Animals." By W. D. Halliburton, 

 M.D., B.Sc. (Lond.), Sharpey Physiological Scholar, 

 University College, London. Communicated by Professor 

 E. A. S chafer, F.R.S. (from the Physiological Laboratory, 

 University College, London). Received December 24, 

 1884. 



At Professor Lankester's snggestion I have submitted to chemical 

 analysis the cartilages occurring in Sepia and in Limulus. 



The basis of the cartilage is a chondrin-like body which gives the 

 reactions of mucin and gelatin ; indeed chondrin, as it occurs in the 

 ordinary hyaline cartilage of vertebrates, is now regarded by many 

 as a mechanical mixture of these two bodies. But in the cartilages 

 of the two invertebrates in question the gelatinous element is 

 exceedingly small, and no gelatinisation occurs on the cooling of 

 the hot watery extract. 



In addition to this, however, the cartilage of both these animals 

 differs from that of vertebrates in containing a certain small per- 

 centage of chitin. In the case of Limulus 1*01 per cent., and of 

 Sepia 122 per cent, of chitin in the dry state is present. 



I have also demonstrated that chitin exists in the liver of the king 

 crab, though whether in the connective tissue or in the liver cells 

 themselves I cannot say. The connective tissue element is very 

 abundant in the liver of this animal, and it seems probable, looking 

 at the part that chitin plays as a supporting structure in these 

 animals, that it really forms in this instance a partial basis for the 

 connective tissue. 



The way in which chitin was demonstrated to exist was the same 

 in all three cases, viz. : — 



I. After digesting with potash, a residue insoluble in boiliDg alkalies 

 remains behind. 



