302 SPONGIN. HYALIN. TUNICIN. [BOOK I. 



Reactions Conchiolin is insoluble in dilute acids and in alka- 



of Conchiolin. line leys. It is soluble in hot concentrated hydrochloric 

 acid. When boiled with dilute sulphuric acid it furnishes leucine and 

 110 sugar-like body. By the two last characters it is as clearly dis- 

 tinguished from chitin, as by its much smaller amount of nitrogen. 



Spongln. 



When sponge is boiled with dilute hydrochloric acid, then with caustic 

 soda, water, ether and alcohol, there is left a body to which the name of 

 Spongin has been given. 



This body (if a definite body it be), so far as it has been investigated, 

 appears to have the following composition : 



Carbon 47*44 



Hydrogen 6 -30 



Nitrogen 1615 



Oxygen 30-11 



When boiled with water it yields no gelatin. 



When boiled with dilute sulphuric acid it yields leucine and glycocine, 

 but no tyrosine. 



Hyalin. 



This term is applied to the principal constituent of the walls of hydatid 

 cysts. 



Prepara- Hydatid cysts, emptied of their contents, are boiled in 



tion. water, then in alcohol and ether. The residual matter is 



soluble when heated in water (under pressure) at 150C. The solution is 

 precipitated by alcohol, neutral and basic lead acetate, and by mercuric 

 nitrate. 



Elementary The composition is said to vary according as the substance 



composition. { s prepared from old or young cysts. 



Composition of hyalin (Liicke 1 ). 



(1) ( 2 ) 



From young cysts. From old cysts. 



C ' 44-1 45-3 



H 67 6-5 



N 4-5 5-2 



O 44-7 430 



Products of When dissolved in strong sulphuric acid or boiled in 



decomposi- dilute sulphuric acid, hyalin is said to yield 50 p.c. of its 

 tion - weight of a dextrogyrous sugar, susceptible of the alco- 



holic fermentation. 



Tunicin or Animal Cellulose, C 6 H 10 5 . 



This body, closely resembling, if not identical with, the cellulose so 

 widely distributed throughout the vegetable kingdom, occurs in the 

 mantle of the Tunicata. 



1 Liicke, Virchow's Arcliiv, Vol. xix. p. 189. 



