[Vol. 2 



790 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



This was brought to a boil with constant stirring, and when 

 an opalescent solution resulted the paste was transferred with 

 rinsing to a 2-liter flask containing about 500 cc. of boiling 

 water. The lot was boiled under a reflux condenser for two 

 hours, cooled, and made up to a liter. Although, as is stated 

 by Clark, this treatment is very effective in breaking down 

 the starch grain physically, no detectable hydrolysis takes 

 place, and the additional advantage is gained in obtaining a 

 paste that will not settle out, even after long standing. Two 

 per cent toluene was employed as an antiseptic if the starch 

 were not to be used immediately. 



Since all dextrin obtainable contained some reducing sugar, 

 it was found necessary to purify it by making a concentrated 

 solution in hot distilled water, and then precipitating out with 

 several volumes of 95 per cent alcohol. The dextrin was 

 caught on a filter paper and dried at a low constant tem- 

 perature. 



Laminarin, a dextrin-like carbohydrate found in many of 

 the Fucaceae, was isolated from Laminaria Agardhii accord- 

 ing to the method employed by Kylin ('13), with some few 

 slight modifications. Freshly collected Laminaria was 

 crushed in the usual way and 1,680 grams of the pulp were 

 boiled with 7 liters of water for 24 hours, water being added 

 from time to time to replace that lost through evaporation. 

 The extract was then filtered off through a double thickness of 

 cheese cloth, and the residue pressed out with a tourniquet. 

 About 3,000 cc. of a dirty brown filtrate were obtained which 

 was divided into three lots of 1,000 cc. each. To the first of 

 these was added a concentrated Ba(OH) 2 solution until the 



precipitation of the inorganic matter was complete. The pre- 



was 



filter in a Buchner funnel 



filtrate being a clear, golden-colored liquid. The 



& 



material in the other two lots was precipitated with basic 

 lead acetate, the liquid filtered off through cotton, and the 

 excess of lead removed with H 2 S. The solutions were filtered 

 while hot through double filter paper to remove the lead 

 sulphide, and then the excess of H 2 S was driven off with 

 heat. The three portions were first evaporated to about one- 



