SPECIAL METHODS. l6l 



at present to regard them as a special modification of cellu- 

 lose, which is commonly termed fungus-cellulose. 



It should be remarked that, according to the researches of 

 K. Richter (I), the membranes of a large number of fungi 

 give the reactions for pure cellulose after being first treated 

 for a long time with caustic potash. But in many cases the 

 caustic potash must act for a week. 



On the other hand, W. Hoffmeister (I, 254) has lately ob- 

 tained from the fructification of Boletus edulis, by the use of 

 methods always successful with the higher plants, no com- 

 pounds giving the reactions of cellulose. The membranes of 

 this fungus are, according to his researches, characterized by 

 being completely soluble in concentrated hydrochloric acid 

 and caustic potash. 



284. The Membranes of the Bacteria. There can now be 

 no doubt that the Bacteria possess a solid membrane. In 

 most cases its presence may be readily demonstrated by 

 plasmolyzing the organisms (cf. 431 and 463). 



No reliable statements can be made at present as to the 

 chemical constitution of these membranes. They seem, 

 moreover, to consist in part of cellulose; at least, W. Hoff- 

 meister (I, 253) has isolated a substance reacting like cellu- 

 lose from a species of Bacillus not exactly determined. 



6. Paragalactan-like Substances (Hemicelluloses). 



285. Reiss and E. Schulze have shown that, especially 

 in the cell-walls of seeds with considerable thickenings of 

 the walls, carbohydrates occur which differ essentially from 

 cellulose and are dissolved at germination, like the other 

 reserve materials of the seed. One of these substances is 

 called by Reiss reserve-cellulose, another, by Schulze, para- 

 galactan. But it is probable that various related com- 

 pounds exist. All these substances can at present best be 

 grouped under the name proposed by E. Schulze, " Paraga- 

 lactan-like compounds." 



[Schulze's later studies (II) afford ground for distinguish- 

 ing this group of substances from cellulose as hemicellidoses. 

 He finds that they become soluble, with the formation of 



