382 PRINCIPLES OF SOIL MICROBIOLOGY 



4.0 per cent of material (3.3 per cent fat and 0.5 per cent cholesterol) ; 

 alcohol extracted 12 per cent (sugars, lecithin, bases, amino acids, purine 

 bodies); water soluble portion, 28 per cent (sugars, glycogen, amino 

 acids, purine bases, etc.); and residue was made up of 30 per cent 

 protein, 10 per cent amorphous carbohydrate (para-iso-dextrin) and 

 6 per cent chitin. Lower fungi are also capable of synthesizing soluble 

 phosphatides. 39 



The lipoids in the cell wall are primarily responsible for the difficulty 

 with which bacterial proteins are digested. When gram-negative 

 bacteria are treated with flowing steam or with lipoid soluble sub- 

 stances, the digestibility is greatly increased. 40 Gram-positive bac- 

 teria (Bac. cereus, Bac. subtilis) are more easily oxidizable (isoelectric 

 point at pH 2.0 to 3.0) than gram-negative bacteria {Bad. coli, Bad. 

 aerogenes, isoelectric point at pH 5.0). Bacteria are also found to 

 possess a distinct amphoteric character. 41 The place of glycogen may be 

 taken by other reserve carbohydrates, as mycodextran and mycoga- 

 lactan found in young cultures of Pen. expansum and Asp. niger. 42 The 

 starch content of fungi was found 43 to be influenced by the nitrogen- 

 carbohydrate ratio of the medium: the lower the ratio, the greater is 

 the starch formation in the cells of the fungi. Cramer 44 previously 

 obtained from the spores of Pen. glaucum 17 per cent of "spore starch." 

 This was, probably, an impure preparation of mycodextran contami- 

 nated by some other carbohydrate, giving the iodine reaction. Galac- 

 tans have been reported in bacterial slime by Schardinger. 45 A number 



39 Grafe, V., and Magistris, H. Zur Chemie und Physiologie der Pflanzen- 

 phosphatide. II. Die wasserloslichen Phosphatide aus Aspergillus oryzae. 

 Biochem. Ztschr., 162: 366-398. 1925. 



40 Dukes, C. E. The digestibility of bacteria. Brit. Med. Jour. I, 430-432. 

 1922. 



41 Stearn, E. W., and Stearn, A. E. A study of the chemical differentiation of 

 bacteria. Jour. Bact., 10: 13-23. 1925. 



42 Dox, A. W., and Neidig, R. E. The soluble polysaccharides of lower fungi. 

 I. Mycodextran, a new polysaccharide in Penicillium expansion. Jour. Biol. 

 Chem., 18: 167-175. 1914; 19: 235-237. 1914; 20: 83-S5. 1915. 



43 Schmidt, D. tJber die PilzstJirke (Amylose) bei Aspergillus niger v. Tgh. 

 und einige Bemerkungen uber ihren diastatischen Abbau. Biochem. Ztschr. 

 158: 223-252. 1925. 



44 Cramer, E. Die Zusammensetzung der Sporen von Penicillium glaucum 

 und ihre Beziehung zu der Widerstandsfahigkeit derselben gegen iiussere Ein- 

 fliisse. Arch. Hyg., 20: 197-210. 1894. 



45 Schardinger, F. Uber die Garprodukte eines schleimbildenden Bacillus in 

 Rohrzuckerlosungen und die Zusammensetzung eines aus dem Schleime isolierten 

 Kohlehydrates. Centrbl. Bakt. II, 8: 144-147, 175-180. 1902. 



