188 NOTES ON CETRARIA ISLANDICA 



and dried. There resulted an almost white, tasteless, odorless 

 powder, soluble in hot water, insoluble in cold water, free 

 from nitrogenous matter, and yielding about \ per cent of 

 ash. 



Hydration by dilute acid. In each trial a weighed quantity 

 of lichenin was boiled for twelve hours with 2 per cent 

 hydrochloric acid, and the resultant sugar determined in the 

 neutralized fluid by the Allihn gravimetric method. The 

 specific rotation was likewise ascertained and osazones were 

 prepared. 



L 1.0936 grams lichenin (ash-free) yielded on hydration 1.097 grams dex- 

 trose. Assuming a hydration equivalent to that of starch, 1.0936 grams 

 lichenin should yield 1.215 grams sugar. 



II. (a) In a solution of hydration products containing 1.53 per cent sugar 

 (determined as dextrose), in a 200 mm. tube an average of five polari- 

 scopic readings gave a rotation of +1.6. Then (a) D = +52.2. 

 (b) In a solution containing 0.51 per cent sugar in a 220 mm. tube, an 

 average of six readings gave a rotation of +0.6. Then (o) D = +53.1. 

 The specific rotation of dextrose, (a) D = +52.5. 



in. The osazones of the sugar formed were prepared with phenylhydrazin 

 in the usual manner, and recrystallized four times from alcohol. 

 M. p. 199-201 C. 

 The melting point of phenylglucosazone = 204 C. 



The experiments thus indicate an almost complete hydration 

 of lichenin, analogous in its results to the conversion of 

 ordinary starch. 



Action of enzymes and dilute HOI. In order to determine 

 the possible fate of ingested lichenin in the alimentary canal, 

 the behavior of the carbohydrate towards the ordinary amylo- 

 lytic enzymes was reinvestigated. The following typical 

 experiments are selected from the protocols : 



LAI per cent solution of lichenin in boiling water was prepared and 

 placed in a bath at 38 C. Most of the material stays in solution ; a 

 portion separates out at this temperature. Saliva was added and the 

 solution was tested for reducing sugars from time to time, with 

 Fehling's solution. No reaction was obtained after forty-Jive minutes. 

 To one portion ordinary starch paste (1 per cent) was now added. 

 The solution reached the " achromic point" to iodine solution* in one 



* Cf . Gamgee, Physiological Chemistry of the Animal Body, 1893, ii, p. 57. 



