The author's researches extend over a typical range of products obtained from _Boletus edulis, Agaricus campestris, Cantharellus cibarius, Morchella esculenta, Polyporus officinalis, Penicillium glaucum_, and certain undetermined species. The method of purification consisted mainly in (a) exhaustive treatments with ether and boiling alcohol, (b) digestion with alkaline hydrate (1-2 p.ct. NaOH) in the cold, (c) acid hydrolysis (2-3 p.ct. H_{2}SO_{4}) at 95 deg.-100 deg., followed by a chloroxidation treatment by the processes of Schulze or Hoffmeister, and final alkaline hydrolysis. The products, i.e. residues, thus obtained were different in essential points from the celluloses isolated from the tissues of phanerogams similarly treated. Only in exceptional cases do they give blue reactions with iodine in presence of zinc chloride or sulphuric acid. The colourations are brown to red. They resist the action of cuprammonium solutions. They are for the most part soluble in alkaline hydrate solution (5-10 p.ct. NaOH) in the cold. They give small yields (1-2 p.ct.) of furfural on boiling with 10 p.ct. HCl.Aq. Elementary analyses gave the following results, which are important in establishing the presence of a notable proportion of nitrogen, which has certainly been overlooked by the earlier observers:-- _________________________________________________________ | | | | | | 'Cellulose' or residue from | C | H | N | |______________________________________|______|_____|_____| | | | | | | Boletus edulis (Schulze process) | 42.4 | 6.5 | 3.9 | | Boletus edulis (Hoffmeister process) | 44.6 | 6.3 | 3.6 | | Polyporus off. | 43.7 | 6.5 | 0.7 | | Cantharellus cib. | 44.9 | 6.8 | 3.0 | | Agaricus campestris | 44.3 | 6.6 | 3.6 | | Botrytis | 42.1 | 6.3 | 3.9 | | Penicillium glaucum | | | 3.3 | | Morchella esculenta | | | 2.5 | |______________________________________|______|_____|_____| It is next shown that this residual nitrogen is not in the form of residual proteids (1) by direct tests, all of which gave negative results, and (2) indirectly by the high degree of resistance to both alkaline and acid hydrolysis. The 'celluloses' are attacked by boiling dilute acids (1 p.ct. H_{2}SO_{4}), losing in weight from 10 to 23 p.ct., the dissolved products having a cupric reduction value about 50 p.ct. that of an equal weight of dextrose. As an extreme hydrolytic treatment the products were dissolved in 70 p.ct. H_{2}SO_{4}, allowed to stand 24 hours, then considerably diluted (to 3 p.ct. H_{2}SO_{4}) and boiled to complete the inversion. The yields of glucose, calculated from the cupric reduction, were as follows:--