CONSTITUTION OF MESOGLCEA OP ALOYONIUM DIGITATUM. 389 



Note on the Chemical Constitution of the 

 Mesogloea of Alcyonium digitatum. 



By 



^W. Laiig^doii BroAVii, B.A., 



Late Hutchinson Research Student, St. John's College, Cambridge. 

 [From the Physiological Laboratory, Cambridge.] 



The main organic constituent of the mesogloea in Alcy- 

 onium digitatum would appear to belong to that class of 

 bodies described by Kruckenberg^ as hyalogens, so widely found 

 among Invertebrate skeletal structures. Hyalogen is charac- 

 terised by its insolubility, and its conversion by various re- 

 agents (e. g. 5 per cent, solution of caustic soda) into a soluble 

 substance, hyalin. Hyalin is practically a mucin, yielding on 

 decomposition a proteid-like body and a carbohydrate. 



I. The following experiments show that mucin is readily 

 obtainable from the mesogloea ; whether, in life, any of it is 

 present as such, or whether it is derived from a hyalogen by 

 the necessary preliminary treatment, it is, of course, difficult 

 to say. 



Fresh specimens, freed as far as possible from cellular layers, 

 were washed well with distilled water and minced. They were 

 then extracted with a 5 per cent, salt solution to remove any 

 globulins, and left under lime water for seventy-two hours. The 

 filtrate was then treated with acetic acid. A white precipitate 

 was obtained, which, on standing for some hours, settled ; it was 

 then filtered oflF, and washed with water acidulated with acetic 

 acid. It was again dissolved in lime water and re-precipitated. 

 The collected precipitate was boiled with 2 per cent, sulphuric 



* Kruckenberg, * Zeit. f. Biol.,' xxii. 



